Don't generate vapi files during make distcheck
Don't generate vapi files during make distcheck

Due to some missing vapi files in vala 0.14.2 libchamplain's
vapi files cannot be generated with this version. Because
this vala version is commonly deployed, make distcheck often
fails. As a workaround, use the pregenerated vapi files instead.

Distrotech/libchamplain,Distrotech/libchamplain,Distrotech/libchamplain,Distrotech/libchamplain,Distrotech/libchamplain