Fix for CVE CVE-2016-10167
DOS vulnerability in gdImageCreateFromGd2Ctx()

Change based on commit at:

https://github.com/libgd/libgd/commit/fe9ed49dafa993e3af96b6a5a589efeea9bfb36f

--- gd_gd2.c.orig	2017-01-31 07:09:38.043472825 +0000
+++ gd_gd2.c	2017-01-31 07:40:06.395740258 +0000
@@ -414,10 +414,9 @@
 			{
 			  if (!gdGetInt (&im->tpixels[y][x], in))
 			    {
-			      /*printf("EOF while reading\n"); */
-			      /*gdImageDestroy(im); */
-			      /*return 0; */
-			      im->tpixels[y][x] = 0;
+			      fprintf (stderr, "gd2: EOF while reading\n");
+			      gdImageDestroy(im);
+			      return NULL;
 			    }
 			}
 		      else
@@ -425,10 +424,9 @@
 			  int ch;
 			  if (!gdGetByte (&ch, in))
 			    {
-			      /*printf("EOF while reading\n"); */
-			      /*gdImageDestroy(im); */
-			      /*return 0; */
-			      ch = 0;
+			      fprintf (stderr, "gd2: EOF while reading\n");
+			      gdImageDestroy(im);
+			      return NULL;
 			    }
 			  im->pixels[y][x] = ch;
 			}