st/mesa: Do not use draw module in OpenGL ES build.

This removes references to symbols in draw module for OpenGL ES build.
As OpenGL ES does not support feedback/selection mode, draw module is
used in pathes that will never be reached.  However, if the symbols are
referenced, it will bloat the final shared libraries unnecessarily.
This is serious when LLVM is enabled.

src/mesa/state_tracker/st_program.c

@@ -65,8 +65,10 @@ st_vp_release_varients( struct st_context *st,
       if (vpv->driver_shader) 
          cso_delete_vertex_shader(st->cso_context, vpv->driver_shader);
       
+#if FEATURE_feedback || FEATURE_rastpos
       if (vpv->draw_shader)
          draw_delete_vertex_shader( st->draw, vpv->draw_shader );
+#endif
       
       if (vpv->tgsi.tokens)
          st_free_tokens(vpv->tgsi.tokens);