vrend: move last used shader program in front of the list

With that shaders that are used more frequently will remain at the
top of the list, and since the search in the shader program list is
linear, this should save some time.

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>

src/vrend_renderer.c

@@ -1662,9 +1662,12 @@ static struct vrend_linked_shader_program *lookup_cs_shader_program(struct vrend
    LIST_FOR_EACH_ENTRY(ent, &ctx->sub->programs, head) {
       if (!ent->ss[PIPE_SHADER_COMPUTE])
          continue;
-      if (ent->ss[PIPE_SHADER_COMPUTE]->id == cs_id)
+      if (ent->ss[PIPE_SHADER_COMPUTE]->id == cs_id) {
+         list_del(&ent->head);
+         list_add(&ent->head, &ctx->sub->programs);
          return ent;
       }
+   }
    return NULL;
 }
 
@@ -1697,6 +1700,11 @@ static struct vrend_linked_shader_program *lookup_shader_program(struct vrend_co
          continue;
       return ent;
    }
+
+   /* put the entry in front */
+   list_del(&ent->head);
+   list_add(&ent->head, &ctx->sub->programs);
+
    return NULL;
 }