slic3r: now it builds but the tests fail with perl 5.16

And I cannot seem to stop the tests from running!! Anyway, the tests
fail for a good reason (the program would be useless with it) so this is
not ready yet.

TODO: try with perl 5.14? Or wait for slic3r to handle perl 5.16 locale
issues with '.' and ',' in floating point numbers.