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.

wpiutil/src/main/native/cpp/raw_istream.cpp

@@ -0,0 +1,133 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2015-2018 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "wpi/raw_istream.h"
+
+#ifdef _WIN32
+#include <io.h>
+#else
+#include <unistd.h>
+#endif
+
+#include <cstdlib>
+#include <cstring>
+
+#include "wpi/FileSystem.h"
+#include "wpi/SmallVector.h"
+#include "wpi/StringRef.h"
+
+#if defined(_MSC_VER)
+#ifndef STDIN_FILENO
+#define STDIN_FILENO 0
+#endif
+#ifndef STDOUT_FILENO
+#define STDOUT_FILENO 1
+#endif
+#ifndef STDERR_FILENO
+#define STDERR_FILENO 2
+#endif
+#endif
+
+using namespace wpi;
+
+StringRef raw_istream::getline(SmallVectorImpl<char>& buf, int maxLen) {
+  buf.clear();
+  for (int i = 0; i < maxLen; ++i) {
+    char c;
+    read(c);
+    if (has_error()) return StringRef{buf.data(), buf.size()};
+    if (c == '\r') continue;
+    buf.push_back(c);
+    if (c == '\n') break;
+  }
+  return StringRef{buf.data(), buf.size()};
+}
+
+raw_mem_istream::raw_mem_istream(StringRef mem)
+    : raw_mem_istream(mem.data(), mem.size()) {}
+
+void raw_mem_istream::close() {}
+
+size_t raw_mem_istream::in_avail() const { return m_left; }
+
+void raw_mem_istream::read_impl(void* data, size_t len) {
+  if (len > m_left) {
+    error_detected();
+    return;
+  }
+  std::memcpy(data, m_cur, len);
+  m_cur += len;
+  m_left -= len;
+}
+
+static int getFD(const Twine& Filename, std::error_code& EC) {
+  // Handle "-" as stdin. Note that when we do this, we consider ourself
+  // the owner of stdin. This means that we can do things like close the
+  // file descriptor when we're done and set the "binary" flag globally.
+  if (Filename.isSingleStringRef() && Filename.getSingleStringRef() == "-") {
+    EC = std::error_code();
+    return STDIN_FILENO;
+  }
+
+  int FD;
+
+  EC = sys::fs::openFileForRead(Filename, FD);
+  if (EC) return -1;
+
+  EC = std::error_code();
+  return FD;
+}
+
+raw_fd_istream::raw_fd_istream(const Twine& filename, std::error_code& ec,
+                               size_t bufSize)
+    : raw_fd_istream(getFD(filename, ec), true, bufSize) {}
+
+raw_fd_istream::raw_fd_istream(int fd, bool shouldClose, size_t bufSize)
+    : m_bufSize(bufSize), m_fd(fd), m_shouldClose(shouldClose) {
+  m_cur = m_end = m_buf = static_cast<char*>(std::malloc(bufSize));
+}
+
+raw_fd_istream::~raw_fd_istream() {
+  if (m_shouldClose) close();
+  std::free(m_buf);
+}
+
+void raw_fd_istream::close() {
+  if (m_fd >= 0) {
+    ::close(m_fd);
+    m_fd = -1;
+  }
+}
+
+size_t raw_fd_istream::in_avail() const { return m_end - m_cur; }
+
+void raw_fd_istream::read_impl(void* data, size_t len) {
+  size_t left = m_end - m_cur;
+  if (left < len) {
+    // not enough data
+    if (m_cur == m_end) {
+#ifdef _WIN32
+      int count = ::_read(m_fd, m_buf, m_bufSize);
+#else
+      ssize_t count = ::read(m_fd, m_buf, m_bufSize);
+#endif
+      if (count <= 0) {
+        error_detected();
+        return;
+      }
+      m_cur = m_buf;
+      m_end = m_buf + count;
+      return read_impl(data, len);
+    }
+
+    std::memcpy(data, m_cur, left);
+    return read_impl(static_cast<char*>(data) + left, len - left);
+  }
+
+  std::memcpy(data, m_cur, len);
+  m_cur += len;
+}