Move entirety of llvm namespace to wpi namespace.

During shared library loading, a different libLLVM can be pulled in, causing
llvm symbols from dependent libraries to resolve to that library instead of
this one. This has been seen in the wild with the Mesa OpenGL implementation
in JavaFX applications (see wpilibsuite/shuffleboard#361).

This is clearly a very breaking change. For some level of backwards
compatibility, a namespace alias from llvm to wpi is performed in the "llvm"
headers.  Unfortunately, forward declarations of llvm classes will still break,
but compilers seem to generate clear error messages in those cases
("namespace alias 'llvm' not allowed here, assuming 'wpi'").

This change also moves all the wpiutil headers to a single "wpi" subdirectory
from the previously split "llvm", "support", "tcpsockets", and "udpsockets".
Shim headers will be added for backwards compatibility in a later commit.

hal/src/main/native/sim/DriverStation.cpp

@@ -16,8 +16,8 @@
 #include <cstring>
 #include <string>
 
-#include <support/condition_variable.h>
-#include <support/mutex.h>
+#include <wpi/condition_variable.h>
+#include <wpi/mutex.h>
 
 #include "MockData/DriverStationDataInternal.h"
 #include "MockData/MockHooks.h"

hal/src/main/native/sim/Extensions.cpp

@@ -7,8 +7,8 @@
 
 #include "HAL/Extensions.h"
 
-#include <llvm/SmallString.h>
-#include <llvm/StringRef.h>
+#include <wpi/SmallString.h>
+#include <wpi/StringRef.h>
 
 #include "HAL/HAL.h"
 
@@ -46,7 +46,7 @@ int HAL_LoadOneExtension(const char* library) {
   HTYPE handle = DLOPEN(library);
 #if !defined(WIN32) && !defined(_WIN32)
   if (!handle) {
-    llvm::SmallString<128> libraryName("lib");
+    wpi::SmallString<128> libraryName("lib");
     libraryName += library;
 #if defined(__APPLE__)
     libraryName += ".dylib";
@@ -73,13 +73,13 @@ int HAL_LoadOneExtension(const char* library) {
  */
 int HAL_LoadExtensions(void) {
   int rc = 1;
-  llvm::SmallVector<llvm::StringRef, 2> libraries;
+  wpi::SmallVector<wpi::StringRef, 2> libraries;
   const char* e = std::getenv("HALSIM_EXTENSIONS");
   if (!e) return rc;
-  llvm::StringRef env{e};
+  wpi::StringRef env{e};
   env.split(libraries, DELIM, -1, false);
   for (auto& libref : libraries) {
-    llvm::SmallString<128> library(libref);
+    wpi::SmallString<128> library(libref);
     rc = HAL_LoadOneExtension(library.c_str());
     if (rc < 0) break;
   }

hal/src/main/native/sim/HAL.cpp

@@ -7,7 +7,7 @@
 
 #include "HAL/HAL.h"
 
-#include <llvm/raw_ostream.h>
+#include <wpi/raw_ostream.h>
 
 #include "ErrorsInternal.h"
 #include "HAL/DriverStation.h"
@@ -263,7 +263,7 @@ HAL_Bool HAL_Initialize(int32_t timeout, int32_t mode) {
 
   hal::init::InitializeHAL();
 
-  llvm::outs().SetUnbuffered();
+  wpi::outs().SetUnbuffered();
   if (HAL_LoadExtensions() < 0) return false;
   hal::RestartTiming();
   HAL_InitializeDriverStation();

hal/src/main/native/sim/Interrupts.cpp

@@ -9,7 +9,7 @@
 
 #include <memory>
 
-#include <support/condition_variable.h>
+#include <wpi/condition_variable.h>
 
 #include "AnalogInternal.h"
 #include "DigitalInternal.h"

hal/src/main/native/sim/MockData/AccelerometerDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/AccelerometerData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/AnalogGyroDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/AnalogGyroData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/AnalogInDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/AnalogInData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/AnalogOutDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/AnalogOutData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/AnalogTriggerDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/AnalogTriggerData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/CanDataInternal.h

@@ -11,7 +11,7 @@
 #include <limits>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/CanData.h"
 #include "MockData/NotifyCallbackHelpers.h"

hal/src/main/native/sim/MockData/DIODataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/DIOData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/DigitalPWMDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/DigitalPWMData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/DriverStationDataInternal.h

@@ -11,7 +11,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/DriverStationData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/EncoderDataInternal.h

@@ -11,7 +11,7 @@
 #include <limits>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/EncoderData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/HALValueInternal.h

@@ -11,7 +11,7 @@
 #include <string>
 
 #include "MockData/HALValue.h"
-#include "MockData/llvm/StringRef.h"
+#include "MockData/wpi/StringRef.h"
 
 namespace hal {
 
@@ -19,9 +19,9 @@ class Value;
 
 void ConvertToC(const Value& in, HAL_Value* out);
 std::shared_ptr<Value> ConvertFromC(const HAL_Value& value);
-void ConvertToC(llvm::StringRef in, HALString* out);
-inline llvm::StringRef ConvertFromC(const HALString& str) {
-  return llvm::StringRef(str.str, str.len);
+void ConvertToC(wpi::StringRef in, HALString* out);
+inline wpi::StringRef ConvertFromC(const HALString& str) {
+  return wpi::StringRef(str.str, str.len);
 }
 
 }  // namespace hal

hal/src/main/native/sim/MockData/I2CDataInternal.h

@@ -11,7 +11,7 @@
 #include <limits>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/I2CData.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/PCMDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "../PortsInternal.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/PDPDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "../PortsInternal.h"
 #include "MockData/NotifyListenerVector.h"

hal/src/main/native/sim/MockData/PWMDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/NotifyListenerVector.h"
 #include "MockData/PWMData.h"

hal/src/main/native/sim/MockData/RelayDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/NotifyListenerVector.h"
 #include "MockData/RelayData.h"

hal/src/main/native/sim/MockData/RoboRioDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/NotifyListenerVector.h"
 #include "MockData/RoboRioData.h"

hal/src/main/native/sim/MockData/SPIAccelerometerDataInternal.h

@@ -10,7 +10,7 @@
 #include <atomic>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/NotifyListenerVector.h"
 #include "MockData/SPIAccelerometerData.h"

hal/src/main/native/sim/MockData/SPIDataInternal.h

@@ -11,7 +11,7 @@
 #include <limits>
 #include <memory>
 
-#include <support/mutex.h>
+#include <wpi/mutex.h>
 
 #include "MockData/NotifyListenerVector.h"
 #include "MockData/SPIData.h"

hal/src/main/native/sim/MockHooks.cpp

@@ -10,7 +10,7 @@
 #include <cstdio>
 #include <thread>
 
-#include <support/timestamp.h>
+#include <wpi/timestamp.h>
 
 #include "MockHooksInternal.h"
 

hal/src/main/native/sim/Notifier.cpp

@@ -9,9 +9,9 @@
 
 #include <chrono>
 
-#include <support/condition_variable.h>
-#include <support/mutex.h>
-#include <support/timestamp.h>
+#include <wpi/condition_variable.h>
+#include <wpi/mutex.h>
+#include <wpi/timestamp.h>
 
 #include "HAL/HAL.h"
 #include "HAL/cpp/fpga_clock.h"