Fix error recovery in toplev::finalize.

PR ipa/104648

gcc/ChangeLog:

	* main.cc (main): Use flag_checking instead of CHECKING_P
	and run toplev::finalize only if there is not error seen.

gcc/testsuite/ChangeLog:

	* g++.dg/pr104648.C: New test.

gcc/main.cc

@@ -37,9 +37,9 @@ main (int argc, char **argv)
 		 true /* init_signals */);
 
   int r = toplev.main (argc, argv);
-#if CHECKING_P
-  toplev.finalize ();
-#endif
+
+  if (flag_checking && !seen_error ())
+    toplev.finalize ();
 
   return r;
 }

gcc/testsuite/g++.dg/pr104648.C

@@ -0,0 +1,9 @@
+// { dg-do compile }
+// { dg-options "-fvtable-verify=preinit" }
+
+struct A {};
+struct B : virtual A
+{
+  B () {};
+  B () {}; /* { dg-error "cannot be overloaded with" } */
+};