btrfs: place all boolean fields together in struct find_free_extent_ctl

btrfs: place all boolean fields together in struct find_free_extent_ctl

Move the 'retry_uncached' and 'hint' fields close to the other boolean
fields so that we remove a hole from the structure and reduce its size
from 136 bytes down to 128 bytes. Currently this structure is only
allocated in the stack of btrfs_reserve_extent().

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>