Fixing up a few inconsistencies in configure.ac (#306)

Options that specify --with-logfile-dir, or --with-plugin-dir, or --with-runtime-dir needs to be specified using AC_ARG_WITH, not AC_ARG_ENABLE.

If you try to specify --without-openssl, then the conditions should be tested against = "xyes". There is a case where the option is either blank or is set to "xno" and the former case wasn't properly handled.

Signed-off-by: Eivind Næss <eivnaes@yahoo.com>