Make ECM a dependency for all frameworks

Summary:
Also, add a temporary workaround for ECM requiring lrelease/lconvert host
tools if the KF5 sources include translations (which they do when using
tags). We of course need to fix that eventually, but right now that just
prevents anything from building.

Reviewers: cordlandwehr

Reviewed By: cordlandwehr

Subscribers: Frameworks

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D6976