When Kleopatra is not fully initialized the
updates from the ReaderStatus would block widgets
that try to react to the key infos received by
the Readerstatus.

This fixes a crash where a readerstatus update
with an uninitalized cache caused the openpgpwidget
to wait for the keycache even when it was destroyed
by closing the mainwindow.

part of:
GnuPG-Bug-Id: T5962