xfs: move error injection tags into their own file

Move the error injection tag names into a libxfs header so that we can
share it between kernel and userspace.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index f179bdf..da0abc8 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -30,6 +30,7 @@
 #include "xfs_bmap_btree.h"
 #include "xfs_bmap.h"
 #include "xfs_bmap_util.h"
+#include "xfs_errortag.h"
 #include "xfs_error.h"
 #include "xfs_trans.h"
 #include "xfs_trans_space.h"