Also check in return.cocci

This one is much more tricky to use though, certainly not for
automation purposes.

tools/coccinelle/return.cocci

+/*
+ * Our code style inherited from FreeBSD explicitly requires brackets around a
+ * function's return (value). The trick is to always add the parenthesis and
+ * then undo the cases where we ended with two sets of them.
+ *
+ * It has the annoying effect of joining lines that were broken because of
+ * the same code style and this needs to be fixed by hand.
+ *
+ * This does not apply to lib/libvgz/ as this is mostly bundled code and one
+ * quick way to undo changes there after running this patch is:
+ *
+ *     git checkout -- lib/libvgz/
+ *
+ * Once libvgz is out of the way, one quick way to unbreak lines that had the
+ * parenthesis in place is:
+ *
+ *     git checkout --patch
+ *
+ * An interactive prompt will ask what to do for each hunk of updated code and
+ * replying 'y' to a false positive undoes the change on disk.
+ */
+
+@@
+expression rv;
+@@
+
+- return rv;
++ return (rv);
+
+@@
+expression rv;
+@@
+
+- return ((rv));
++ return (rv);