ipfilter: Load optionlist prior to ippool invocation

As a safety precaution df381bec2d2b limits ippool hash table size to 1K.
This causes any legitimely large hash table to fail to load. The
htable_size_max ipf tuneable adjusts this but the adjustment is made
in the ipfilter rc script, invoked after the ippool script (because it
depends on ippool). Let's load the ipfilter_optionlist in ippool as well.
ipfilter_optionlist load will also occur in the ipfilter rc script in case
the user uses ipfilter without ippool.

Fixes: df381bec2d2b
MFC after: 3 days