[clang] [flang] [flang][Frontend] Implement printing defined macros via -dM (PR #87627)

[Krzysztof Parzyszek via cfe-commits]

kparzysz wrote:

The Windows build has the same failure as before (it's a known build breakage):
```
error LNK2019: unresolved external symbol _FortranAioSetForm referenced in function "private: virtual void __cdecl ExternalIOTests_TestWriteAfterEndfile_Test::TestBody(void)" (?TestBody at ExternalIOTests_TestWriteAfterEndfile_Test@@EEAAXXZ)
```

https://github.com/llvm/llvm-project/pull/87627