osd: Optimized EC proc_master_log fix roll-forward logic when shard is absent

osd: Optimized EC proc_master_log fix roll-forward logic when shard is absent

Fix bug in optimized EC code where proc_master_log incorrectly did not
roll forward a write if one of the written shards is missing in the current
epoch and there is a stray version of that shard that did not receive the
write.

As long as the currently present shards that participated in les and were
updated by a write have the update then the write should be rolled-forward.

Signed-off-by: Bill Scales <bill_scales@uk.ibm.com>
(cherry picked from commit e0e8117769a8b30b2856f940ab9fc00ad1e04f63)