Use the right buffer sizes in GLX visual attributes

src/platform/nix/main.cpp

@@ -169,6 +169,10 @@ int main(int argc, char **argv) {
         GLX_RGBA,
         GLX_DOUBLEBUFFER,
         GLX_DEPTH_SIZE, 24,
+        GLX_RED_SIZE, 8,
+        GLX_GREEN_SIZE, 8,
+        GLX_BLUE_SIZE, 8,
+        GLX_ALPHA_SIZE, 8,
         0
     };