filesetup: use zonerange for map and LFSR with zonemode=strided

filesetup: use zonerange for map and LFSR with zonemode=strided

When a random map is enabled, cover only the current zone when run with
zonemode=strided. This ensures that when we reach the end of the zone we
wrap around back into the current zone instead of accessing blocks
outside of the zone.

In addition, when an LFSR is used, constrain the blocks generated to the
current zone. Previously, the LFSR random_generator would ignore the
strided zonemode setting.

Fixes: https://github.com/axboe/fio/issues/809
Signed-off-by: Jens Axboe <axboe@kernel.dk>