[clang] [compiler-rt] [llvm] [PAC][AArch64] Support init/fini array signing (PR #96478)

[Piotr Sobczak via cfe-commits]

piotrAMD wrote:

I am getting build errors with gcc. Any ideas?
```
llvm-project/compiler-rt/lib/builtins/crtbegin.c:11:18: error: missing binary operator before token "("
     11 | #if __has_feature(ptrauth_init_fini)
        |                  ^
llvm-project/compiler-rt/lib/builtins/crtbegin.c:53:18: error: missing binary operator before token "("
     53 | #if __has_feature(ptrauth_init_fini)
        |                  ^
llvm-project/compiler-rt/lib/builtins/crtbegin.c:124:18: error: missing binary operator before token "("
    124 | #if __has_feature(ptrauth_init_fini)
    
```
   

https://github.com/llvm/llvm-project/pull/96478