mod_ssl: unset FIPS mode only if we set it.

If FIPS mode is set by default per openssl lib/module, we should not
unset it on restart or it might never be set again.

PR 63136


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1853133 13f79535-47bb-0310-9956-ffa450edef68