[clang] [compiler-rt] [libcxx] [llvm] [cmake] switch to CMake's native `check_{compiler,linker}_flag` (PR #96171)

[Rainer Orth via llvm-commits]

rorth wrote:

This patch broke the [Solaris/amd64](https://lab.llvm.org/staging/#/builders/120/builds/485) and [Solaris/sparcv9](https://lab.llvm.org/buildbot/#/builders/13/builds/1287) buildbots.

https://github.com/llvm/llvm-project/pull/96171