[clang] [clang-cl] Fix value of __FUNCTION__ in MSVC mode. (PR #67592)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> @AaronBallman By pretty printed you mean the use of **PRETTY_FUNCTION** right?

No, I mean using the `DeclPrinter` and `TypePrinter` interfaces that are used to implement `-ast-print`:
https://github.com/llvm/llvm-project/blob/32d16b64d3125e76f65d7d88a302a33618eb0e6e/clang/lib/AST/DeclPrinter.cpp#L65
https://github.com/llvm/llvm-project/blob/32d16b64d3125e76f65d7d88a302a33618eb0e6e/clang/lib/AST/TypePrinter.cpp#L120

https://github.com/llvm/llvm-project/pull/67592