Work around the GLEW issue on Wayland

When running the client using SDL's Wayland driver, glewInit() was
returning GLEW_ERROR_NO_GLX_DISPLAY. This was messing up our OpenGL
state because we were bailing out of initContext(). We don't use any GLX
extensions, so it seems like it's safe for us to just ignore this and
continue.

Fixes #377

Author: blast007

src/ogl/OpenGLGState.cxx

@@ -1323,9 +1323,13 @@ void OpenGLGState::initContext()
     }
 
     GLenum err = glewInit();
-    if (GLEW_OK != err)
+    // Running the client using SDL's Wayland driver causes glewInit() to return GLEW_ERROR_NO_GLX_DISPLAY. We do not
+    // check for or use GLX extensions, so I think it's safe to allow for this error code.
+    // https://github.com/nigels-com/glew/issues/417
+    // https://github.com/BZFlag-Dev/bzflag/issues/377
+    if (GLEW_OK != err && GLEW_ERROR_NO_GLX_DISPLAY != err)
     {
-        printf("Error: %s\n", glewGetErrorString(err));
+        printf("initContext() Error: %s\n", glewGetErrorString(err));
         return;
     }