We can't handle the correct state when blocking via a tasks
mbActive bool, as this also schedules the task and starts the
scheduler timer. So reintroduce a bool for the unblock state.

Change-Id: I40991d0160b058fae3803fab002dc036fc0b0339
Reviewed-on: https://gerrit.libreoffice.org/59692
Tested-by: Jenkins
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>