Don't double count security updates in MounNotifier.
Review Request #126284 - Created Dec. 8, 2015 and submitted
MuonNotifier::extendedMessage() and the securty update count to the total after calling MounNotfier::updatesCount() which already does this.
Fixes 347284 when only sercurity updates are needed. However on my system there seems to be another issue related to non-security updates. Untested in this case.