lib-patch-mode.sh: Fix permission

In the same sprit as 4848509 (Fix permissions on test scripts,
2007-04-13), t/lib-patch-mode.sh should not be executable.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/lib-patch-mode.sh

@@ -1,3 +1,5 @@
+: included from t2016 and others
+
 . ./test-lib.sh
 
 set_state () {