Subject: bug#70557: Fix compilation of Vala files conditionally added to _SOURCES

From: Karl Berry <[email-masked]>
Date: Fri, 26 Apr 2024 16:53:23 -0600

Reuben, any chance you can whomp up a test for this patch?

I don't see a problem with the change, but it's always better to add a
test against future regressions, etc. --thanks, karl.