Sort output from find

[bmwiedemann]

because we want reproducible output even though filesystem order is undeterministic

See https://reproducible-builds.org/ for why this is good.

Without the patch, @files was used in 2 places but only sorted in 1

Was filed earlier at https://rt.cpan.org/Public/Bug/Display.html?id=122336

[skaji]

@bmwiedemann thanks!