nviz: Use direct rendering; Indirect rendering disabled by default in modern Xorg (since 1.17?)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@72939 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/nviz/render.c

@@ -113,7 +113,7 @@ int Nviz_create_render_window(struct render_window *rwin, void *display,
         return -1;
     }
         
-    rwin->contextId = glXCreateContext(rwin->displayId, v, NULL, GL_FALSE);
+    rwin->contextId = glXCreateContext(rwin->displayId, v, NULL, GL_TRUE);
 
     if (!rwin->contextId) {
 	G_warning(_("Unable to create rendering context"));