Fix the first two or three build failures. Judging by what comes next

Fix the first two or three build failures. Judging by what comes next
it is probably not worth trying to patch this any further, rather than
updating it (although there are/were some problems with things it may
depend on) but maybe making some progress will inspire someone else to
take this up.

In particular I tracked down the lossage where it was looking for vala
1.0 and the current vala versions are 0.12 and 0.14. It seems that
what someone optimistically intended at some point to be vala-1.0
(after vala-0.9) ended up released as vala-0.10.