[compiler-rt] [compiler-rt][AArch64] Enable libc-free builtins Linux build (PR #125922)

[John Ericson via llvm-commits]

Ericson2314 wrote:

@efriedma-quic I started replying here, but then wrote https://github.com/llvm/llvm-project/issues/127227 as there is I think a larger discussion to be had beyond just the change currently in this PR.

https://github.com/llvm/llvm-project/pull/125922