Improve OpenSSL legacy build process

Summary:
Strange issues occur when runas is used on FreeBSD:

• first, an issue in SaltStack for csh support
• then, in Perl, setgid complains PATH isn't secure
• finally, a double link error occur at the end

It works like a charm building as root, using sudo directly in the build script.

Test Plan: salt-call --local state.sls roles/shellserver/userland-software/openssl-legacy

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D2089