Ocfs2/move_extents: Add basic framework and source files for extent moving.

Adding new files move_extents.[c|h] and fill it with nothing but
only a context structure.

Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
diff --git a/fs/ocfs2/Makefile b/fs/ocfs2/Makefile
index d8a0313..f17e58b 100644
--- a/fs/ocfs2/Makefile
+++ b/fs/ocfs2/Makefile
@@ -30,6 +30,7 @@
 	namei.o 		\
 	refcounttree.o		\
 	reservations.o		\
+	move_extents.o		\
 	resize.o		\
 	slot_map.o 		\
 	suballoc.o 		\