Btrfs: get rid of sparse warnings

make C=2 fs/btrfs/ CF=-D__CHECK_ENDIAN__

I tried to filter out the warnings for which patches have already
been sent to the mailing list, pending for inclusion in btrfs-next.

All these changes should be obviously safe.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/send.c

@@ -54,8 +54,8 @@ struct fs_path {
 
 			char *buf;
 			int buf_len;
-			int reversed:1;
-			int virtual_mem:1;
+			unsigned int reversed:1;
+			unsigned int virtual_mem:1;
 			char inline_buf[];
 		};
 		char pad[PAGE_SIZE];