BDB_ALIASES and BDB_SUBENTRIES cleanup

servers/slapd/back-bdb/add.c

servers/slapd/back-bdb/attribute.c

servers/slapd/back-bdb/back-bdb.h

servers/slapd/back-bdb/bind.c

servers/slapd/back-bdb/config.c

servers/slapd/back-bdb/delete.c

servers/slapd/back-bdb/filterindex.c

servers/slapd/back-bdb/group.c

servers/slapd/back-bdb/init.c

servers/slapd/back-bdb/modify.c

servers/slapd/back-bdb/modrdn.c

servers/slapd/back-bdb/passwd.c

servers/slapd/back-bdb/search.c