[OpenCL] Fix version reporting of C++ for OpenCL 2021

C++ for OpenCL version 2021 and later are expected to consist of a
major version number only. Therefore, a different constructor for
`VersionTuple` needs to be called when reporting language version.

Differential Revision: https://reviews.llvm.org/D108379

clang/lib/Basic/LangOptions.cpp

@@ -47,6 +47,8 @@ bool LangOptions::isNoBuiltinFunc(StringRef FuncName) const {
 
 VersionTuple LangOptions::getOpenCLVersionTuple() const {
   const int Ver = OpenCLCPlusPlus ? OpenCLCPlusPlusVersion : OpenCLVersion;
+  if (OpenCLCPlusPlus && Ver != 100)
+    return VersionTuple(Ver / 100);
   return VersionTuple(Ver / 100, (Ver % 100) / 10);
 }