secureserver.pl: make OpenSSL CApath and cert absolute path values

Recent stunnel versions (5.08) seem to have trouble with relative
paths on Windows. This turns the relative paths into absolute ones.
secureserver.pl: update Windows detection and fix path conversion
secureserver.pl: clean up formatting of config and fix verbose output

Verbose output was not matching the actual configuration file,
because FIPS and Windows conditions were ignored.