[compiler-rt] [compiler-rt][MSVC][CMake] Wrap Linker flags for ICX (PR #118496)

[Mészáros Gergely via llvm-commits]

Maetveis wrote:

> So this PR I probably broke building compiler-rt with clang (not clang-cl) on Windows, which is not something I was aware of anyone using. I'll see if I can reproduce and fix that.

So I can reproduce the linker failure, but I'm also getting other failures too, notably this one for example:
```plaintext
D:/iusers/gergelym/llvm-project/compiler-rt/lib/builtins/mulxc3.c:20:35: error: unknown type name 'xf_float'
   20 | COMPILER_RT_ABI Lcomplex __mulxc3(xf_float __a, xf_float __b, xf_float __c,
```

I don't think compiler-rt ever compiled cleanly when using `clang` (instead of `clang-cl`) on Windows. It is as the rest of LLVM not tested this way. @BukeBeyond I would encourage you to figure out why the runtimes build is being set up this way, instead of trying to fix compiler-rt with clang.


https://github.com/llvm/llvm-project/pull/118496