i965: Make sure that the shader_time report at context destroy happens.

Otherwise, you end up with some report from within a second of context
destroy, which is now what you really want for testing the impact of
changes

src/mesa/drivers/dri/i965/brw_vtbl.c

@@ -71,6 +71,9 @@ static void brw_destroy_context( struct intel_context *intel )
    struct brw_context *brw = brw_context(&intel->ctx);
 
    if (INTEL_DEBUG & DEBUG_SHADER_TIME) {
+      /* Force a report. */
+      brw->shader_time.report_time = 0;
+
       brw_collect_and_report_shader_time(brw);
       brw_destroy_shader_time(brw);
    }