compat_clock_getres shouldn't return -EFAULT if res == NULL

Description within the patch.

-Arun

For clock_getres(clockid_t clock_id, struct timespec *res), the specification says "If res is NULL, the clock resolution is not returned." So this kind of call should succeed. The current implementation returns -EFAULT.

The patch fixes the bug in compat_clock_getres().

@@ -531,7 +531,7 @@
 	err = sys_clock_getres(which_clock,
 			       (struct timespec __user *) &ts);
 	set_fs(oldfs);
-	if (!err && put_compat_timespec(&ts, tp))
+	if (!err && tp && put_compat_timespec(&ts, tp))
 		return -EFAULT; 
 	return err;
 } 

Looks good.

I'll queue it up. I seem to have ~200 patches to deal with, mostly non-trivial :(