console-gl: add opengl rendering helper functions

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

ui/shader/texture-blit.frag

@@ -0,0 +1,10 @@
+
+#version 300 es
+
+uniform sampler2D image;
+in  mediump vec2 ex_tex_coord;
+out mediump vec4 out_frag_color;
+
+void main(void) {
+     out_frag_color = texture(image, ex_tex_coord);
+}