st/mesa: don't load state parameters if there are none

Out of 7063 shaders from my shader-db:
- 6564 (93%) shaders don't have any state parameters.
- 347 (5%) shaders have 1 state parameter for WPOS lowering.
- The remaining 2% have more state parameters, usually matrices.

Reviewed-by: Brian Paul <brianp@vmware.com>

src/mesa/state_tracker/st_atom_constbuf.c

@@ -73,7 +73,8 @@ void st_upload_constants( struct st_context *st,
        * the parameters list are explicitly set by the user with glUniform,
        * glProgramParameter(), etc.
        */
-      _mesa_load_state_parameters(st->ctx, params);
+      if (params->StateFlags)
+         _mesa_load_state_parameters(st->ctx, params);
 
       /* We always need to get a new buffer, to keep the drivers simple and
        * avoid gratuitous rendering synchronization.