[clang] [lldb] [llvm] Remove some `try_compile` CMake checks for compiler flags (PR #92953)

[Nikita Popov via cfe-commits]

nikic wrote:

> > FYI this causes a minor compile-time improvement in stage1 builds using gcc: https://llvm-compile-time-tracker.com/compare.php?from=32c3561d44aa792ef08d72b5a4c342c9965bc4c2&to=4feae05c6abda364a9295aecfa600d7d4e7dfeb6&stat=instructions:u While that's nice, it does suggest that the flags are not the same as before.
> 
> @nikic Can you elaborate on those numbers? Do you say that Clang (compiled with GCC) which compiles those tests works faster now?

Yes, exactly. Clang compiled with GCC is faster. Clang compiled with Clang is not. So it seems like something changed in the options for GCC.

https://github.com/llvm/llvm-project/pull/92953