[compiler-rt] [compiler-rt] Add CMake option to enable execute-only code generation on AArch64 (PR #140555)

[Csanád Hajdú via llvm-commits]

Il-Capitano wrote:

@ldionne [commented on my RFC](https://discourse.llvm.org/t/rfc-execute-only-code-support-for-runtime-libraries-on-aarch64/86180/4) about using a single CMake option for all runtime libraries.

If there aren't any opposing views, I'm fine with making that change, so if you have any thoughts (either in support of the change or opposing it), please comment on the RFC. Thanks!

https://github.com/llvm/llvm-project/pull/140555