rfc2589 support (ITS#4293)

clients/tools/Makefile.in

clients/tools/ldapexop.c

configure.in

doc/man/man5/slapo-dds.5

include/ldap.h

libraries/libldap/Makefile.in

libraries/libldap/dds.c

libraries/libldap_r/Makefile.in

servers/slapd/bconfig.c

servers/slapd/controls.c

servers/slapd/overlays/Makefile.in

servers/slapd/overlays/dds.c

servers/slapd/schema_prep.c

servers/slapd/slap.h

tests/data/dds.out

tests/data/slapd-dds.conf

tests/run.in

tests/scripts/conf.sh

tests/scripts/defines.sh

tests/scripts/test046-dds