[clang] [clang][PAC][NFC] Provide addition support macros to ptrauth.h (PR #161027)

[Oliver Hunt via cfe-commits]

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@@ -384,9 +444,23 @@ typedef __UINTPTR_TYPE__ ptrauth_generic_signature_t;
 #define ptrauth_cxx_vtable_pointer(key, address_discrimination,                \
                                    extra_discrimination...)
 
+#define __ptrauth_function_pointer(__typekey)
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ojhunt wrote:

as @atrosinenko it's to support general headers using standard qualifiers without having to duplicate every declaration :D

https://github.com/llvm/llvm-project/pull/161027