Avoid a warning on pointer casting, NFC

[GBuella]

Summary

The warning was:

unittests/Passes/PluginsTest.cpp:30:23: warning: ISO C++ forbids casting between pointer-to-function and pointer-to-object [-Wpedantic]
   void *Ptr = (void *)anchor;
                          ^

[philip.pfaffe]

LGTM. Thanks for fixing!

unittests/Passes/PluginsTest.cpp

 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Transforms/Scalar/LoopPassManager.h"
 #include "gtest/gtest.h"
 
 #include "TestPlugin.h"
 
+#include <cstdint>
+
 using namespace llvm;
 
 void anchor() {}
 
 static std::string LibPath(const std::string Name = "TestPlugin") {
   const std::vector<testing::internal::string> &Argvs =
       testing::internal::GetArgvs();
   const char *Argv0 = Argvs.size() > 0 ? Argvs[0].c_str() : "PluginsTests";
-  void *Ptr = (void *)anchor;
+  void *Ptr = (void *)(intptr_t)anchor;
   std::string Path = sys::fs::getMainExecutable(Argv0, Ptr);
   llvm::SmallString<256> Buf{sys::path::parent_path(Path)};
   sys::path::append(Buf, (Name + ".so").c_str());
   return Buf.str();
 }
 
 TEST(PluginsTests, LoadPlugin) {
   auto PluginPath = LibPath();