[clang] [clang] fix uefi target for aarch64 & x86_64 (PR #120632)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> > Should we have an entry for `-fdefine-target-os-macros` as well?
> 
> I think so, it wouldn't be a bad idea.
> 
> > Also needs a test
> 
> I might need some guidance on adding a test since I'm not fully familiar with the clang side of LLVM.

Check  `./clang/test/Preprocessor/init.c`

https://github.com/llvm/llvm-project/pull/120632