i965/vs: Pack uniform registers before optimization

We don't expect uniform accesses to generally go away from being dead
code at this point, and we will want to have uniforms packed before
spilling them out to pull constants when we are forced to do that.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/drivers/dri/i965/brw_vec4_emit.cpp

@@ -607,6 +607,7 @@ vec4_visitor::run()
     */
    move_grf_array_access_to_scratch();
    move_uniform_array_access_to_pull_constants();
+   pack_uniform_registers();
 
    bool progress;
    do {
@@ -614,7 +615,6 @@ vec4_visitor::run()
       progress = dead_code_eliminate() || progress;
    } while (progress);
 
-   pack_uniform_registers();
 
    if (failed)
       return false;