import magic.vapi for libmagic

Small library for displaying info about file formats/types (known by its file
utility).

Origin: https://github.com/ony/runPE/blob/master/magic.vapi
import sensors.vapi for libsensors

Publically accessible functions provided by the sensors library
http://www.lm-sensors.org/

Origin: https://github.com/ony/heatoff/blob/master/sensors.vapi
import cpufreq.vapi for access to cpufrequtils

vapi to userspace library for the Linux kernel cpufreq subsystem

Origin: https://github.com/ony/heatoff/blob/master/cpufreq.vapi
gcrypt: add key derivation support and some hash algorithms

Also, clean up some warnings from newer versions of Vala related to
unowned/weak and an extra CCode annotation.