x32: fix waitid()

It needs 64bit rusage and 32bit siginfo.  glibc never calls it with
non-NULL rusage pointer, or we would've seen breakage already...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/compat.c b/kernel/compat.c
index 0770ac5..e5cc33c 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -587,7 +587,11 @@
 		return ret;
 
 	if (uru) {
-		ret = put_compat_rusage(&ru, uru);
+		/* sys_waitid() overwrites everything in ru */
+		if (COMPAT_USE_64BIT_TIME)
+			ret = copy_to_user(uru, &ru, sizeof(ru));
+		else
+			ret = put_compat_rusage(&ru, uru);
 		if (ret)
 			return ret;
 	}