repobuild/wheezy: get jessie libzmq3, not wheezy

Same as was just implemented for precise to get trusty's libzmq3

Signed-off-by: Dan Mick <dan.mick@inktank.com>
repobuild: reprepro on precise doesn't support GetInRelease

Signed-off-by: Dan Mick <dan.mick@inktank.com>