crossbuild is broken because of dependency conflicts

[Andrea Bernabei]

Building armhf unity8 in a chroot with sbuild currently doesn't work because of dependency issues.

How to reproduce:
1) mk-sbuild --target=armhf vivid
2) add overlay ppa to the chroot, upgrade packages etc
3) sbuild --host=armhf --build=amd64 vivid-amd64-armhf

Building fails during the installation of unit8 builddeps:
libconnectivity-qt1-dev:armhf : Depends: libconnectivity-qt1:armhf (= 0.5.1+15.04.20150611-0ubuntu1) but it is not going to be installed

Installing libconnectivity-qt1-dev:armhf manually in the chroot works, but if you try installing unity8 builddeps after installing libconnectivity-qt1-dev:armhf, apt will try to remove libconnectivity

There is probably a dependency conflict where one of the builddeps of unity8 conflicts with libconnectivity-qt1-dev

More details:
if you install libconnectivity-qt1-dev:armhf, then install builddeps and let it remove libconn-qt1-dev:armhf, and then try installing the builddeps again, the conflict become more evident, here's the log:
http://pastebin.ubuntu.com/11735156/