Add a cmake build to distcheck to ensure that we distribute all the files
necessary to do a cmake build.

Note that this does mean that anyone doing "make distcheck" needs cmake.

Bug: 10331
Change-Id: I4360a305aa7f6ffc1b5a5dffad24b928eed45016
Reviewed-on: https://code.wireshark.org/review/3326
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Jeff Morriss <jeff.morriss.ws@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Jeff Morriss <jeff.morriss.ws@gmail.com>