ext4: sparse fixes

* Change EXT4_HAS_*_FEATURE to return a boolean
* Add a function prototype for ext4_fiemap() in ext4.h
* Make ext4_ext_fiemap_cb() and ext4_xattr_fiemap() be static functions
* Add lock annotations to mb_free_blocks()

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 91e06f8..bcd5ffa 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3907,7 +3907,7 @@
 	ext4_fsblk_t		block;
 	int			inodes_per_block, inode_offset;
 
-	iloc->bh = 0;
+	iloc->bh = NULL;
 	if (!ext4_valid_inum(sb, inode->i_ino))
 		return -EIO;