add recent minilibx linux as submodule

libs/minilibx_opengl_20191021/mlx_opengl.h

@@ -0,0 +1,21 @@
+/*
+**
+** mlx_opengl.h 
+**
+** public include, use it after mlx.h
+** designed only for minilibx_macos
+**
+*/
+
+void    *mlx_new_opengl_window(void *mlx_ptr, int size_x, int size_y, char *title);
+
+/* create an opengl window. put_image & pixel_put & string_put do not work there. */
+
+int	mlx_opengl_swap_buffers(void *win_ptr);
+
+/* the created window is double buffered. Use this funct to swap buffers */
+/* this funct will call glFlush(). Don't call it. */
+
+int	mlx_opengl_window_set_context(void *win_ptr);
+
+/* in case multiple opengl windows are present, change opengl active context */