gnu: red-eclipse: Fix build.

Add a patch from the upstream repository [1] that resolves some errors that
prevent the package from building [2].

1: https://github.com/red-eclipse/base/commit/b16b4963c1ad81bb9ef784bc49
2: error: ‘____gammal_r_finite’ was not declared in this scope

* gnu/packages/games.scm (red-eclipse)[source] Add patch.
* gnu/packages/patches/red-eclipse-remove-gamma-name-hack.patch: New file
* gnu/local.mk (dist_patch_DATA): Add new patch.

gnu/local.mk

@@ -1197,6 +1197,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/rct-add-missing-headers.patch		\
   %D%/packages/patches/readline-link-ncurses.patch		\
   %D%/packages/patches/readline-6.2-CVE-2014-2524.patch		\
+  %D%/packages/patches/red-eclipse-remove-gamma-name-hack.patch	\
   %D%/packages/patches/reposurgeon-add-missing-docbook-files.patch	\
   %D%/packages/patches/reptyr-fix-gcc-7.patch			\
   %D%/packages/patches/ripperx-missing-file.patch		\

gnu/packages/games.scm

@@ -2843,7 +2843,9 @@ (define-public red-eclipse
                 (file-name (string-append name "-" version ".tar.gz"))
                 (sha256
                  (base32
-                  "1vs9k6f5fgsiy1n72imlqm8khjwm8cryc08zwd4gr7yxlxv45bs0"))))
+                  "1vs9k6f5fgsiy1n72imlqm8khjwm8cryc08zwd4gr7yxlxv45bs0"))
+                (patches
+                 (search-patches "red-eclipse-remove-gamma-name-hack.patch"))))
       (build-system gnu-build-system)
       (arguments
        `(#:tests? #f            ; no check target

gnu/packages/patches/red-eclipse-remove-gamma-name-hack.patch

@@ -0,0 +1,52 @@
+From b16b4963c1ad81bb9ef784bc4913a4c8ab5f1bb4 Mon Sep 17 00:00:00 2001
+From: Lee Salzman <lsalzman@gmail.com>
+Date: Tue, 12 Sep 2017 14:45:10 -0400
+Subject: [PATCH] remove gamma name hack
+
+---
+ src/engine/main.cpp | 6 +++---
+ src/shared/cube.h   | 8 --------
+ 2 files changed, 3 insertions(+), 11 deletions(-)
+
+diff --git a/src/engine/main.cpp b/src/engine/main.cpp
+index 1032004d..77c9233a 100644
+--- a/src/engine/main.cpp
++++ b/src/engine/main.cpp
+@@ -278,10 +278,10 @@ static void setgamma(int val)
+ }
+ 
+ static int curgamma = 100;
+-VARF(IDF_PERSIST, gamma, 30, 100, 300,
++VARFN(IDF_PERSIST, gamma, reqgamma, 30, 100, 300,
+ {
+-    if(initing || gamma == curgamma) return;
+-    curgamma = gamma;
++    if(initing || reqgamma == curgamma) return;
++    curgamma = reqgamma;
+     setgamma(curgamma);
+ });
+ 
+diff --git a/src/shared/cube.h b/src/shared/cube.h
+index 3864c492..7ff5e267 100644
+--- a/src/shared/cube.h
++++ b/src/shared/cube.h
+@@ -3,19 +3,11 @@
+ 
+ #define _FILE_OFFSET_BITS 64
+ 
+-#ifdef __GNUC__
+-#define gamma __gamma
+-#endif
+-
+ #ifdef WIN32
+ #define _USE_MATH_DEFINES
+ #endif
+ #include <math.h>
+ 
+-#ifdef __GNUC__
+-#undef gamma
+-#endif
+-
+ #include <string.h>
+ #include <stdio.h>
+ #include <stdlib.h>