Remove some code that was written in 2000 to support OSes that do not
have nanosleep(). nanosleep() has been specified (in POSIX-1.2001) for
almost a decade now, so assume we have it (except on Windows).
Remove the checks for nanosleep and nsleep from configure.ac.
We're removing this code because we honestly believe that nobody will be
affected. If this change negatively impacts you, please file a bug.
These macros should be used instead of -I for things in the tree that
depend on various bits of glib.
also gobject_INCLUDES, gthread_INCLUDES, gmodule_INCLUDES, gio_INCLUDES