xfs: split out transaction reservation code

The transaction reservation size calculations is used by both kernel
and userspace, but most of the transaction code in xfs_trans.c is
kernel specific. Split all the transaction reservation code out into
it's own files to make sharing with userspace simpler. This just
leaves kernel-only definitions in xfs_trans.h, so it doesn't need to
be shared with userspace anymore, either.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
index 695606a..150c670 100644
--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c
@@ -17,6 +17,7 @@
  */
 #include "xfs.h"
 #include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
 #include "xfs_acl.h"
 #include "xfs_attr.h"
 #include "xfs_bmap_btree.h"