Fix possibly uninitialized variable 'so.in_use' reported by Coverity.
Fix possibly uninitialized variable 'so.in_use' reported by Coverity.

GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver,GerHobbelt/civet-webserver