[Bazel] Don't set HAVE_[DE]REGISTER_FRAME on Windows

This is also done based on OS in the GN build
(https://github.com/llvm/llvm-project/blob/24b0df8686/llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn#L193-L203).
Of course the right way would be to set up platform detection, but that
remains TODO.

Reviewed By: csigg

Differential Revision: https://reviews.llvm.org/D107375