Jenkinsfile: Allow partial deployments.

When a packaging target fails to build, deploy the successful builds
to the repository anyway.

* Jenkinsfile (BUILD_OWN_QT): Remove parameter.  The Qt builds are now
implicitly made as part of the regular packaging targets.
(Build packages): Wrap make invocation in a catchError so that the
stage appears as failed while the build is marked as a success, which
allows the 'Sign & deploy packages' stage to run despite packaging
errors.

Change-Id: I5785d154f5e1963aa824576f7f0f62043446456a