Fix interface1.php's expected output

Somewhere in the .filter consolidation and cleanup,
the bit that stripped the function name was removed. Add it
back.

hphp/test/vm/interface1.php.expectf

@@ -1 +1 @@
-HipHop Fatal error: Class D contains abstract method (foo) and must therefore be declared abstract or implement the remaining methods in %s on line 8
+HipHop Fatal error: Class D contains abstract method (%s) and must therefore be declared abstract or implement the remaining methods in %s on line 8