Security update for freerdp (important)

This update for freerdp fixes the following issues:

 - CVE-2017-2834: Out-of-bounds write in license_recv() (bsc#1050714)

 - CVE-2017-2835: Out-of-bounds write in rdp_recv_tpkt_pdu (bsc#1050712)

 - CVE-2017-2836: Rdp Client Read Server Proprietary Certificate Denial
   of Service (bsc#1050699)

 - CVE-2017-2837: Client GCC Read Server Security Data DoS (bsc#1050704)

 - CVE-2017-2838: Client License Read Product Info Denial of Service
   Vulnerability (bsc#1050708)

 - CVE-2017-2839: Client License Read Challenge Packet Denial of Service
   (bsc#1050711)