fs: move the buffer_heads_over_limit stub to buffer_head.h

Move the !CONFIG_BLOCK stub to the same place as the non-stub
declaration.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/blkdev.h

@@ -1838,7 +1838,6 @@ struct block_device;
 /*
  * stubs for when the block layer is configured out
  */
-#define buffer_heads_over_limit 0
 
 static inline long nr_blockdev_pages(void)
 {

include/linux/buffer_head.h

@@ -406,6 +406,7 @@ static inline int inode_has_buffers(struct inode *inode) { return 0; }
 static inline void invalidate_inode_buffers(struct inode *inode) {}
 static inline int remove_inode_buffers(struct inode *inode) { return 1; }
 static inline int sync_mapping_buffers(struct address_space *mapping) { return 0; }
+#define buffer_heads_over_limit 0
 
 #endif /* CONFIG_BLOCK */
 #endif /* _LINUX_BUFFER_HEAD_H */