Update private_typeinfo's `is_equal` implementation after r361913

The libc++ typeinfo implementation is being improved to better
handle non-merged type names.

This patch takes advantage of that more correct behavior by delegating
to std::type_infos default operator== instead of doing pointer equality
ourselves.

However, libc++ still expects unique RTTI by default, and so we
should still fall back to strcmp when explicitly requested.

llvm-svn: 361916

libcxxabi/src/private_typeinfo.cpp

@@ -58,14 +58,12 @@ static inline
 bool
 is_equal(const std::type_info* x, const std::type_info* y, bool use_strcmp)
 {
-#ifndef _WIN32
+    // Use std::type_info's default comparison unless we've explicitly asked
+    // for strcmp.
     if (!use_strcmp)
-        return x == y;
-    return strcmp(x->name(), y->name()) == 0;
-#else
-    (void) use_strcmp;
-    return (x == y) || (strcmp(x->name(), y->name()) == 0);
-#endif
+        return *x == *y;
+    // Still allow pointer equality to short circut.
+    return x == y || strcmp(x->name(), y->name()) == 0;
 }
 
 namespace __cxxabiv1