[clang] [AArch64][PAC] Support ptrauth builtins and -fptrauth-intrinsics. (PR #65996)

[Ahmed Bougacha via cfe-commits]

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@@ -303,6 +303,10 @@ bool Module::directlyUses(const Module *Requested) {
   if (!Requested->Parent && Requested->Name == "_Builtin_stddef_max_align_t")
     return true;
 
+  // Anyone is allowed to use our builtin ptrauth.h and its accompanying module.
+  if (!Requested->Parent && Requested->Name == "ptrauth")
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ahmedbougacha wrote:

Unfortunately this is needed, to match the (compiler-interface-defining) `ptrauth.h` header file we vend.  (specifically this is to allow usage of `ptrauth.h` from `no_undeclared_interfaces` modules, see ed84df008f609.

https://github.com/llvm/llvm-project/pull/65996