btrfs: fix structs where bitfields and spinlock/atomic share 8B word

On ia64, powerpc64 and sparc64 the bitfield is modified through a RMW cycle and current
gcc rewrites the adjacent 4B word, which in case of a spinlock or atomic has
disaterous effect.

https://lkml.org/lkml/2012/2/1/220

Signed-off-by: David Sterba <dsterba@suse.cz>

fs/btrfs/ctree.h

@@ -886,7 +886,7 @@ struct btrfs_block_rsv {
 	u64 reserved;
 	struct btrfs_space_info *space_info;
 	spinlock_t lock;
-	unsigned int full:1;
+	unsigned int full;
 };
 
 /*

fs/btrfs/extent_map.h

@@ -26,8 +26,8 @@ struct extent_map {
 	unsigned long flags;
 	struct block_device *bdev;
 	atomic_t refs;
-	unsigned int in_tree:1;
-	unsigned int compress_type:4;
+	unsigned int in_tree;
+	unsigned int compress_type;
 };
 
 struct extent_map_tree {