$OpenBSD: patch-lib_glew_include_GL_glew_h,v 1.1 2019/01/28 15:30:56 jsg Exp $

modify embedded copy of glew.h for recent Mesa versions

Mesa >= 18.2.5 has newer OpenGL headers from Khronos which change the
include guards.

Index: lib/glew/include/GL/glew.h
--- lib/glew/include/GL/glew.h.orig
+++ lib/glew/include/GL/glew.h
@@ -93,7 +93,7 @@
 #if defined(__REGAL_H__)
 #error Regal.h included before glew.h
 #endif
-#if defined(__glext_h_) || defined(__GLEXT_H_)
+#if defined(__glext_h_) || defined(__GLEXT_H_) || defined(__gl_glext_h_)
 #error glext.h included before glew.h
 #endif
 #if defined(__gl_ATI_h_)
@@ -108,6 +108,7 @@
 #define __X_GL_H
 #define __glext_h_
 #define __GLEXT_H_
+#define __gl_glext_h_
 #define __gl_ATI_h_
 
 #if defined(_WIN32)
