[llvm] [clang-cl] Fix value of __FUNCTION__ and __FUNC__ in MSVC mode for c++. (PR #66120)

[Zahira Ammarguellat via llvm-commits]

zahiraam wrote:

> Our preference would be to revert the change and reland it later since this doesn't appear to be a quick fix, which is in line with https://llvm.org/docs/DeveloperPolicy.html#patch-reversion-policy

No problem. Go ahead and revert it. Thanks.

https://github.com/llvm/llvm-project/pull/66120