xfs: refactor "does this fork map blocks" predicate

Replace the open-coded checks for whether or not an inode fork maps
blocks with a macro that will implant the code for us.  This helps us
declutter the bmap code a bit.

Note that I had to use a macro instead of a static inline function
because of C header dependency problems between xfs_inode.h and
xfs_inode_fork.h.

Conversion was performed with the following Coccinelle script:

@@
expression ip, w;
@@

- XFS_IFORK_FORMAT(ip, w) == XFS_DINODE_FMT_EXTENTS || XFS_IFORK_FORMAT(ip, w) == XFS_DINODE_FMT_BTREE
+ xfs_ifork_has_extents(ip, w)

@@
expression ip, w;
@@

- XFS_IFORK_FORMAT(ip, w) != XFS_DINODE_FMT_EXTENTS && XFS_IFORK_FORMAT(ip, w) != XFS_DINODE_FMT_BTREE
+ !xfs_ifork_has_extents(ip, w)

@@
expression ip, w;
@@

- XFS_IFORK_FORMAT(ip, w) == XFS_DINODE_FMT_BTREE || XFS_IFORK_FORMAT(ip, w) == XFS_DINODE_FMT_EXTENTS
+ xfs_ifork_has_extents(ip, w)

@@
expression ip, w;
@@

- XFS_IFORK_FORMAT(ip, w) != XFS_DINODE_FMT_BTREE && XFS_IFORK_FORMAT(ip, w) != XFS_DINODE_FMT_EXTENTS
+ !xfs_ifork_has_extents(ip, w)

@@
expression ip, w;
@@

- (xfs_ifork_has_extents(ip, w))
+ xfs_ifork_has_extents(ip, w)

@@
expression ip, w;
@@

- (!xfs_ifork_has_extents(ip, w))
+ !xfs_ifork_has_extents(ip, w)

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>