locking: move all auto_mark logic into process_callbacks()

locking: move all auto_mark logic into process_callbacks()

The caller should not dereference lock_ctx after invoking
process_callbacks(), it might be destroyed already.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11293

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
Autobuild-User(master): Amitay Isaacs <amitay@samba.org>
Autobuild-Date(master): Fri Jun 12 15:28:57 CEST 2015 on sn-devel-104

(Imported from commit b3a18d66c00dba73a3f56a6f95781b4d34db1fe2)