Log Message:
x11/gtkada: Add post-wrapper hack to work around bad gtk2 pkgconfig file

The GTK2 configure script searches in vain for libgmodule.  Since it does
not find it, gmodule-2.0 is not added to the gtk+*-2.0 pkgconfig files.
Since gcc-aux now uses the gold linker which requires explicit linking by
default, gtkada fails to link due to use of gmodule-2.0 symbols within
other libraries.

The true fix needs to happen at the gtk2 package.  A post-wrapper hack has
been added to gtkada to locally append the gtk2 pkgconfig file which
allows building to complete.

This hack should be removed when gtk2's gtk+-2.0.pc file has been fixed.