Why not to use explicit method?

// upp_static_init.cpp
void upp_static_init() {
  {void plugin_gif_init(); plugin_gif_init();}
  // or this way
  #include <plugin/gif/gif.init>
  ...
}

[plugin/gif/gif.init]
{void plugin_gif_init(); plugin_gif_init();}

you'll have control over order of initialization and it looks like ordinary include.
And this file can be easyly generated with small tool.