Use new Devel::FindPerl
Use File::Spec::Functions
Fix skipping on non-unix
t/x2p/find2perl.t: expand output

Currently there is one ok() per test case; split that into 4 ok()s
per case, so that different sorts of failures can be differentiated
(i.e. ability to: run find2perl, run its output, run find, and compare the
outputs.)