vo_opengl: fix OSD with icc-profile after previous commit

This happened to break because the texture unit wasn't reset to 0, which
some code expects. The OSD code in particular set the OSD texture on the
wrong texture unit, with the result that OSD/OSC was not visible.

video/out/opengl/utils.c

@@ -1052,6 +1052,8 @@ void gl_sc_generate(struct gl_shader_cache *sc)
     for (int n = 0; n < sc->num_uniforms; n++)
         update_uniform(gl, entry, &sc->uniforms[n], n);
 
+    gl->ActiveTexture(GL_TEXTURE0);
+
     sc->needs_reset = true;
 }