This fixes the following CVEs:
* FTP: shutdown response buffer overflow CVE-2018-1000300
* RTSP: bad headers buffer over-read CVE-2018-1000301

Change-Id: Ic3229577083286501162aa5979a94ce934739557
Reviewed-on: https://gerrit.libreoffice.org/54418Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Tested-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>