See if this forces version.h to be built.

(It's not being built by the Ubuntu buildboth when it's building the
Debian package.)

Change-Id: Id7866e13ce72cdda4bb7d5cf0362ba7295ff766b
Reviewed-on: https://code.wireshark.org/review/2772
Reviewed-by: Guy Harris <guy@alum.mit.edu>