Check for nullptr return from malloc, calloc, and realloc. (#1023)

These are used in ntcore and cscore.  Add inline null-checking versions
to wpi/memory.h and use them throughout.

cscore/src/main/native/cpp/HttpCameraImpl.cpp

@@ -9,6 +9,7 @@
 
 #include <wpi/STLExtras.h>
 #include <wpi/TCPConnector.h>
+#include <wpi/memory.h>
 #include <wpi/timestamp.h>
 
 #include "Handle.h"
@@ -574,7 +575,8 @@ void CS_SetHttpCameraUrls(CS_Source source, const char** urls, int count,
 
 char** CS_GetHttpCameraUrls(CS_Source source, int* count, CS_Status* status) {
   auto urls = cs::GetHttpCameraUrls(source, status);
-  char** out = static_cast<char**>(std::malloc(urls.size() * sizeof(char*)));
+  char** out =
+      static_cast<char**>(wpi::CheckedMalloc(urls.size() * sizeof(char*)));
   *count = urls.size();
   for (size_t i = 0; i < urls.size(); ++i) out[i] = cs::ConvertToC(urls[i]);
   return out;