gd: add patch for CVE-2014-2497

Fixes CVE-2014-2497 - NULL pointer dereference
Patch from upstream:
https://bitbucket.org/libgd/gd-libgd/commits/463c3bd09bfe8e924e19acad7a2a6af16953a704



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>