vokoscreen-ng fails to cross build from source, because it fails running
lrelease. This failure is swallowed (and constitutes a violation of
Debian policy section 4.6). As a result, later parts consuming the
output fail. The root cause is that running lrelease requires a native
qmake, but Build-Depends do not request one. The attached patch adds the
missing dependency. In a native build, the dependency is implied.

Helmut