ayatana-ido fails to cross build from source because the CMake
instructions hard code the build architecture vapigen. While vapigen
looks architecture-independent on the surface, it uses pkg-config and
thus uses architecture-dependent paths. Hence it fails finding GLib-2.0.
I'm attaching a patch that looks up the correct vapigen via (the
correctly detected) pkg-config. Please consider applying it. Note that
the package already contains a similar change for gir.

Helmut