Throughout, (mainly in fhandler*) fix remaining gcc 4.7 mismatch

warnings between regparm definitions and declarations.
* smallprint.cc (__small_vswprintf): Conditionalize declaration and
setting of l_opt for only x86_64.
* spawn.cc (child_info_spawn::worker): Remove unused 'pid' variable.
* thread.cc (verifyable_object_isvalid): Temporarily define as
non-inline with gcc 4.7+, regardless of target.

winsup/cygwin/fhandler_console.cc

@@ -318,7 +318,7 @@ fhandler_console::mouse_aware (MOUSE_EVENT_RECORD& mouse_event)
 		 || dev_state.use_mouse >= 3));
 }
 
-void __stdcall
+void __reg3
 fhandler_console::read (void *pv, size_t& buflen)
 {
   push_process_state process_state (PID_TTYIN);