fix various issues; line up with new tests

servers/slapd/back-sql/add.c

servers/slapd/back-sql/entry-id.c

servers/slapd/back-sql/external.h

servers/slapd/back-sql/init.c

...ers/slapd/back-sql/rdbms_depend/mysql/testdb_metadata.sql

...ers/slapd/back-sql/rdbms_depend/pgsql/testdb_metadata.sql

servers/slapd/back-sql/schema-map.c

servers/slapd/back-sql/search.c

servers/slapd/back-sql/sql-wrap.c

servers/slapd/back-sql/util.c