test: add test for loading from global folders

Test executes with a copy of the node executable since $PREFIX/lib/node
is relative to the executable location.

PR-URL: https://github.com/nodejs/node/pull/9283


Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: João Reis <reis@janeasystems.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>