In lcm.c there is if (!g_thread_supported ()) g_thread_init (NULL); Since g_thread_supported is defined to 1, function g_thread_init is never called and removed by the optimizing compiler. It anyway would do nothing, since in gthread-impl.c it is:

void g_thread_init (gpointer init) {
  if (init != NULL)
    g_warning ("GThread system no longer supports custom thread implementations.");
}

Therefore the dependency on gthread-2.0 can be removed.