Remove unused variables

clients/gopher/go500gw.c

clients/mail500/main.c

clients/rcpt500/main.c

clients/rcpt500/query.c

clients/ud/main.c

libraries/libldap/charset.c

servers/slapd/back-ldbm/cache.c

servers/slapd/back-ldbm/dn2id.c

servers/slapd/back-ldbm/id2children.c

servers/slapd/back-ldbm/index.c

servers/slapd/back-ldbm/init.c

servers/slapd/back-ldbm/nextid.c

servers/slapd/back-ldbm/search.c

servers/slapd/phonetic.c

servers/slapd/result.c

servers/slapd/schema.c