Btrfs: fix gcc warnings for 32bit compiles

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --cc fs/btrfs/backref.c
Simple merge

diff --cc fs/btrfs/file-item.c
Simple merge

diff --cc fs/btrfs/qgroup.c
Simple merge

diff --cc fs/btrfs/send.c
Simple merge