Update devel/kdevelop and attendants to latest upstream release.

Release notes are at
https://www.kdevelop.org/news/kdevelop-546-released
which says
We today provide a bugfix and localization update release
with version 5.4.6. This release introduces no new features
and as such is a safe and recommended update for everyone
currently using a previous version of KDevelop 5.4.