NumDirectoryGuards now tracks NumEntryGuards by default

Now a user who changes only NumEntryGuards will get the behavior she
expects. Fixes bug 9354; bugfix on 0.2.4.8-alpha.
Merge remote-tracking branch 'arma/bug9354' into maint-0.2.4
Merge remote-tracking branch 'origin/maint-0.2.4'