MB-14183 Before compating update kv_header in old file
MB-14183 Before compating update kv_header in old file

Without this the last header put into the old_file before compaction
begins can carry an outdated kv_header doc where the sequence numbers
updated during the process of the last wal_flush are not reflected.
In this interval if someone tries to open a snapshot they may not find
their latest sequence number and fdb_get_all_snap_markers can return
incorrect results.

Change-Id: I21047119d6737eb4a8d6925d01a4f64f426b6584

hisundar/forestdb,joliss/forestdb,zhaog/forestdb,couchbase/forestdb,jinxuan/forestdb,nvoron23/forestdb,hisundar/forestdb,zhaog/forestdb,couchbase/forestdb,sushmaad/forestdb,sushmaad/forestdb,joliss/forestdb,jinxuan/forestdb,seem-sky/forestdb,nvoron23/forestdb,yyangpan/forestdb,seem-sky/forestdb,wurikiji/forestdb,wurikiji/forestdb,yyangpan/forestdb