merge ext4_claim_free_blocks & ext4_has_free_blocks

Mingming pointed out that ext4_claim_free_blocks & ext4_has_free_blocks
are largely cut & pasted; they can be collapsed/merged as follows.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 4880cc3..b0537c8 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1003,8 +1003,7 @@
 					ext4_lblk_t iblock, ext4_fsblk_t goal,
 					unsigned long *count, int *errp);
 extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
-extern ext4_fsblk_t ext4_has_free_blocks(struct ext4_sb_info *sbi,
-					 s64 nblocks);
+extern int ext4_has_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
 extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
 			ext4_fsblk_t block, unsigned long count, int metadata);
 extern void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,