Add patches required to fix CVE-2008-180[123], taken from rdesktop CVS.

1) An integer underflow error in iso.c when processing RDP requests can
  be exploited to cause a heap-based buffer overflow.
2) An input validation error in rdp.c when processing RDP redirect
  requests can be exploited to cause a BSS-based buffer overflow.
3) A signedness error within "xrealloc()" in rdesktop.c can be exploited
  to cause a heap-based buffer overflow.

(tonnerre)