Log Message:
orc: Fix installation if gtk-doc package is already installed

By default orc is configured with `--disable-gtk-doc'. However, despite that,
it will checks several `gtkdoc-*' tools anyway, ending in a failure during the
installation phase because only a couple of them are available.

Add a kludge via CONFIGURE_ENV to avoid picking up gtkdoc-* tools.

Pointed out by <martin> via PR pkg/52632.