Changed SHA calculation in license checker to assume binary files

[clintongormley]

Related to #12117

Closes #12118

[rmuir]

+1!

[rmuir]

I checked on a windows VM (with all plugins, but not core/ due to tar issues, see below), it works and fixes the checksum issue! thanks!

I think for now, we should just push this one, and keep the checker temporarily disabled on windows because it requires not just perl.exe, but a more complicated setup with unzip.exe and a tar.exe that supports .tar.gz (this one is tricky to find on windows). And I think we should be doing mvn verify builds on windows in jenkins etc, even though we do not today.

Maybe in a followup issue the script could be changed to use http://perldoc.perl.org/Archive/Extract.html or something similar if its generally expected to be bundled with perl?

[clintongormley]

Maybe in a followup issue the script could be changed to use http://perldoc.perl.org/Archive/Extract.html or something similar if its generally expected to be bundled with perl?

Archive::Extract is no longer in perl core. I'll have a look for alternatives