Btrfs-progs: fix the allocator

Btrfs-progs: fix the allocator

The allocator looks for these hints when moving on to another block group which
will make it reset which block group it looks at, when we've already searched
that block group and didn't find any space to allocate, we need to fix this by
just letting the allocator make the determination if the block group is good
enough.  This also fixes a problem where if we couldn't find space in the block
group we were given we'd just error out instead of moving on to the next block
group.  Previously I couldn't fix some file systems that were relatively full,
but with this patch I can now run fsck on them with no allocation errors.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>