[Vala] Vapi duplication in different dir

[中川祥 <matyapiro31 gmail com>]

I have a question now.
I have two version of vapi file for the slightestly same c library and the
file in vapi default dir /usr/share/vala/vapi/ is not complete vapi
file,though my original local file is completed.
The project loads the default dir's file and I have no execution to
change.Does anyone know how to set up CMakelist.txt to load local one and
ignore the default dir one?