Use __PTRAUTH__ macro to detect presence of ptrauth.h include

In llvm/llvm-project#153912, usage of
`__has_feature(ptrauth_intrinsics)` was restricted to Darwin-only, while
`__PTRAUTH__` macro was introduced instead.

This patch makes use of a preprocessor check against `__PTRAUTH__` macro in
addition to previously used `__has_feature(ptrauth_intrinsics)`. The
latter check is kept for backward compatibility.

Author: kovdan01

arch/aarch64/reloc.h

@@ -33,7 +33,7 @@
 #define CRTJMP(pc,sp) __asm__ __volatile__( \
 	"mov sp,%1 ; br %0" : : "r"(pc), "r"(sp) : "memory" )
 
-#if __has_feature(ptrauth_intrinsics)
+#if defined(__PTRAUTH__) || __has_feature(ptrauth_intrinsics)
 
 #include <stdint.h>
 

ldso/dynlink.c

@@ -20,7 +20,7 @@
 #include <dlfcn.h>
 #include <semaphore.h>
 #include <sys/membarrier.h>
-#if __has_feature(ptrauth_intrinsics)
+#if defined(__PTRAUTH__) || __has_feature(ptrauth_intrinsics)
 #include <ptrauth.h>
 #endif
 #include "pthread_impl.h"
@@ -566,7 +566,7 @@ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stri
 				reloc_addr[0] = (size_t)__tlsdesc_dynamic;
 				reloc_addr[1] = (size_t)new;
 			} else {
-#if __has_feature(ptrauth_intrinsics) && !__has_feature(ptrauth_elf_got)
+#if (defined(__PTRAUTH__) || __has_feature(ptrauth_intrinsics)) && !__has_feature(ptrauth_elf_got)
 				reloc_addr[0] = (size_t)ptrauth_strip(&__tlsdesc_static, 0);
 #else
 				reloc_addr[0] = (size_t)__tlsdesc_static;

src/ldso/aarch64/reloc.c

@@ -1,6 +1,6 @@
 #include "reloc.h"
 
-#if __has_feature(ptrauth_intrinsics)
+#if defined(__PTRAUTH__) || __has_feature(ptrauth_intrinsics)
 
 #include <stdint.h>