gl-renderer: Force call to glUseProgram() when activating debug binding

gl-renderer: Force call to glUseProgram() when activating debug binding

When redrawing surfaces, use_shader() checks if the desired shader is
already in use to avoid a call to glUseProgram(). However, once the
debug binding is activated, that same check would prevent the usage of
the recompiled shaders until something cause a different shader to be
passed to use_shader().