btrfs: remove fs/btrfs/compat.h

fs/btrfs/compat.h only contained trivial macro wrappers of drop_nlink()
and inc_nlink().  This doesn't belong in mainline.

Signed-off-by: Zach Brown <zab@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/file.c

@@ -39,7 +39,6 @@
 #include "print-tree.h"
 #include "tree-log.h"
 #include "locking.h"
-#include "compat.h"
 #include "volumes.h"
 
 static struct kmem_cache *btrfs_inode_defrag_cachep;