[compiler-rt] [compiler-rt][test] Remove noisy warnings (PR #191510)

[Dan Liew via llvm-commits]

delcypher wrote:

> > > > `find_compiler_libdir` => `get_path_from_clang` => uses `--target={config.target_triple}` when asking for the runtimes path. Shouldn't clang be returning the i386 path?
> > > 
> > > 
> > > But this point is interesting
> > 
> > 
> > get_path_from_clang is always called target_triple --target=x86_64-unknown-linux-gnu
> 
> Actually it's called
> 
> usr/local/google/home/vitalybuka/src/llvm.git/out/z/./bin/clang', '--target=x86_64-unknown-linux-gnu', '-m64', '-print-runtime-dir' -> lib/clang/23/lib/x86_64-unknown-linux-gnu
> 
> or
> 
> usr/local/google/home/vitalybuka/src/llvm.git/out/z/./bin/clang', '--target=x86_64-unknown-linux-gnu', '-m32', '-print-runtime-dir' -> lib/clang/23/lib/i386-unknown-linux-gnu
> 
> and when we see warning its
> 
> usr/local/google/home/vitalybuka/src/llvm.git/out/z/./bin/clang', '--target=x86_64-unknown-linux-gnu' '-print-runtime-dir' -> lib/clang/23/lib/x86_64-unknown-linux-gnu

So `find_compiler_libdir` is also supported to use `config.target_cflags` too. Does that not contain `-m32`?

```
def find_compiler_libdir():
    """
    Returns the path to library resource directory used
    by the compiler.
    """
    <snip>

    # Try using `-print-runtime-dir`. This is only supported by very new versions of Clang.
    # so allow failure here.
    runtime_dir, clang_cmd = get_path_from_clang(
        shlex.split(config.target_cflags) + ["-print-runtime-dir"], allow_failure=True
    )
```
```

https://github.com/llvm/llvm-project/pull/191510