I didn't set the LICENSE-Var, because the program doesn't have a real "license", just some sentences in the README. I don't know what to do in such cases.
Created attachment 2430 [details] pngcrush-1.5.10.ebuild
what are the sentences? does it qualify for an "as-is" licensing scheme?
pngcrush-1.5.10 committed to Portage tree. I've masked out this version for now, please test it so I can unmask it.