[compiler-rt][test] fix zero_page_pc on arm64e

on arm64e, pointer auth would catch this access violation before asan.
sign the function pointer so pointer auth will ignore this violation and let asan catch it in this test case.

rdar://79652167

Reviewed By: delcypher

Differential Revision: https://reviews.llvm.org/D104828

compiler-rt/test/asan/TestCases/zero_page_pc.cpp

@@ -1,9 +1,17 @@
 // Check that ASan correctly detects SEGV on the zero page.
 // RUN: %clangxx_asan %s -o %t && not %run %t 2>&1 | FileCheck %s
 
+#if __has_feature(ptrauth_calls)
+#  include <ptrauth.h>
+#endif
+
 typedef void void_f();
 int main() {
   void_f *func = (void_f *)0x4;
+#if __has_feature(ptrauth_calls)
+  func = ptrauth_sign_unauthenticated(
+      func, ptrauth_key_function_pointer, 0);
+#endif
   func();
   // x86 reports the SEGV with both address=4 and pc=4.
   // On PowerPC64 ELFv1, the pointer is taken to be a function-descriptor