intel/compiler: Allocate pull_param in assign_constant_locations

Now that everything is nicely ralloc'd, we can allocate the pull_param
array in assign_constant_locations instead of higher up.  We can also
re-allocate the param array so that it's exactly the needed size.  This
should save us some memory because we're not allocating the total needed
param space for both push and pull.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/intel/compiler/brw_vec4_visitor.cpp

@@ -1782,6 +1782,11 @@ vec4_visitor::move_uniform_array_access_to_pull_constants()
       return;
    }
 
+   /* Allocate the pull_params array */
+   assert(stage_prog_data->nr_pull_params == 0);
+   stage_prog_data->pull_param = ralloc_array(mem_ctx, uint32_t,
+                                              this->uniforms * 4);
+
    int pull_constant_loc[this->uniforms];
    memset(pull_constant_loc, -1, sizeof(pull_constant_loc));