ITS#9420 - Fix memory leak in modrdn

Fix provided by grapvar@gmail.com
3 jobs for !210 with its9420 in 34 minutes and 32 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Build
passed #2876
build-gnutls-mit-standalone-lloadd

00:30:02

passed #2874
build-no-threads-no-slapd

00:03:31

passed #2875
build-openssl-heimdal-lloadd

00:31:47