Unbreak with glew->=2.3.0

Index: backports/glew/src/glew.c
--- backports/glew/src/glew.c.orig
+++ backports/glew/src/glew.c
@@ -16156,7 +16156,7 @@ GLboolean GLEWAPIENTRY glewGetExtension (const char* n
 typedef const GLubyte* (GLAPIENTRY * PFNGLGETSTRINGPROC) (GLenum name);
 typedef void (GLAPIENTRY * PFNGLGETINTEGERVPROC) (GLenum pname, GLint *params);
 
-static GLenum GLEWAPIENTRY glewContextInit ()
+GLenum GLEWAPIENTRY glewContextInit ()
 {
   PFNGLGETSTRINGPROC getString;
   const GLubyte* s;
