kernel: Update clone-with-pid patch subject

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

kernel/cr-clone-with-pid-support

 From: Pavel Emelyanov <xemul@openvz.org>
-Subject: [PATCH] Allow processes to be created with specified pid
+Subject: [PATCH] clone: Introduce the CLONE_CHILD_USEPID functionality
 
 When restoring a task (or a set of tasks) we need to recreate them with
 exactly the same pid as they had before. Thus we need the ability to create