osd: write journal header by force when journal write close

osd: write journal header by force when journal write close

osd update the journal header when ceph call FileStore::sync_entry(
ApplyManager::commit_finish -> FileJournal::committed_thru).
But, it doesnot write the journal head until the next transaction
(calling do_write or do_aio_write).

So write jouranl header when journal write close, so that
committed_up_to in journal header is new enough. ceph may
not replay some transaction which has been writen to filestore.

Signed-off-by: Xinze Chi <xmdxcxz@gmail.com>
(cherry picked from commit 8f80ae3fbaba7b0e64b6e4df6c2dddd10ac50e5a)