Update fixes for dbi_open/close, ITS#7515.
Update fixes for dbi_open/close, ITS#7515.

Reset me_dbflags[dbi] when closing DBI, to get rid of MDB_VALID flag.
mdb_env_close(): Re-fix DB-name memleak. DBIs > me_numdbs may exist.

bobek-balinek/BlueJet