gnu: gd: Fix failing test on i686.

* gnu/packages/patches/gd-fix-test-on-i686.patch: New file.
* gnu/local.mk (dist_PATCH_DATA): Add it.
* gnu/packages/gd.scm (gd)[source]: Add the patch.

gnu/local.mk

@@ -514,6 +514,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/gd-CVE-2016-6128.patch			\
   %D%/packages/patches/gd-CVE-2016-6132.patch			\
   %D%/packages/patches/gd-CVE-2016-6214.patch			\
+  %D%/packages/patches/gd-fix-test-on-i686.patch		\
   %D%/packages/patches/gegl-CVE-2012-4433.patch			\
   %D%/packages/patches/geoclue-config.patch			\
   %D%/packages/patches/ghostscript-CVE-2015-3228.patch		\

gnu/packages/gd.scm

@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2013, 2016 Ludovic Courtès <ludo@gnu.org>
-;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
+;;; Copyright © 2015, 2016 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2015 Eric Bavier <bavier@member.fsf.org>
 ;;; Copyright © 2016 Leo Famulari <leo@famulari.name>
 ;;;
@@ -47,7 +47,8 @@
              (uri (string-append
                    "https://github.com/libgd/libgd/releases/download/gd-"
                    version "/libgd-" version ".tar.xz"))
-             (patches (search-patches "gd-CVE-2016-5766.patch"
+             (patches (search-patches "gd-fix-test-on-i686.patch"
+                                      "gd-CVE-2016-5766.patch"
                                       "gd-CVE-2016-6128.patch"
                                       "gd-CVE-2016-6132.patch"
                                       "gd-CVE-2016-6214.patch"))

gnu/packages/patches/gd-fix-test-on-i686.patch

@@ -0,0 +1,34 @@
+Disable part of the gdimagerotate test on architectures such as i686
+where intermediate floating-point operations are done with 80-bit long
+doubles, and typically later rounded to 64-bit doubles.  This double
+rounding causes small differences in the resulting pixel values
+compared with other architectures, causing the image comparison to
+fail.
+
+Patch by Mark H Weaver <mhw@netris.org>.
+
+--- libgd-2.2.2/tests/gdimagerotate/bug00067.c	1969-12-31 19:00:00.000000000 -0500
++++ libgd-2.2.2/tests/gdimagerotate/bug00067.c	2016-07-18 12:19:19.885423132 -0400
+@@ -1,5 +1,6 @@
+ #include <stdio.h>
+ #include <stdlib.h>
++#include <float.h>
+ #include "gd.h"
+ 
+ #include "gdtest.h"
+@@ -41,6 +42,7 @@
+ 			return 1;
+ 		}
+ 
++#if FLT_EVAL_METHOD != 2
+ 		sprintf(filename, "bug00067_%03d_exp.png", angle);
+ 		path = gdTestFilePath2("gdimagerotate", filename);
+ 		if (!gdAssertImageEqualsToFile(path, exp)) {
+@@ -48,6 +50,7 @@
+ 			error += 1;
+ 		}
+ 		free(path);
++#endif
+ 
+ 		gdImageDestroy(exp);
+ 	}