[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.

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