[compiler-rt][ubsan][nfc-ish] Fix a type conversion bug

With llvm#100483, if the inline asm
version of `ptrauth_strip` is used instead of the builtin, the inline
asm implementation will return an unsigned long, causing an incompatible
pointer conversion issue.

Author: alanzhao1

compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cpp

@@ -207,7 +207,8 @@ struct VtablePrefix {
   std::type_info *TypeInfo;
 };
 VtablePrefix *getVtablePrefix(void *Vtable) {
-  Vtable = ptrauth_strip(Vtable, ptrauth_key_cxx_vtable_pointer);
+  Vtable = reinterpret_cast<void *>(
+      ptrauth_strip(Vtable, ptrauth_key_cxx_vtable_pointer));
   VtablePrefix *Vptr = reinterpret_cast<VtablePrefix*>(Vtable);
   VtablePrefix *Prefix = Vptr - 1;
   if (!IsAccessibleMemoryRange((uptr)Prefix, sizeof(VtablePrefix)))