__declspec is not a core Clang language extension. Instead, require...

__declspec is not a core Clang language extension. Instead, require -fms-extensions or -fborland to enable the language extension.

Note: __declspec is also temporarily enabled when compiling for a CUDA target because there are implementation details relying on __declspec(property) support currently. When those details change, __declspec should be disabled for CUDA targets.
llvm-svn: 238238