ffi/ffi — pull request #315 by davispuh (2013-12-12 19:59:54+00:00)
Title: Use Ruby implementation for `which`

In Windows there's no `/dev/null` and it causes error "The System cannot find the path specified". Also in Windows there's no native `which` and it works only because it's included in DevKit.

This Ruby implementation should correctly work for all platforms.