i started to port this, but gave up
Created attachment 263343 [details, diff]
half assed attempt
Looks like netbsd folks did the rest of way here:
+*xv-3.10a-r16 (07 Aug 2011)
+ 07 Aug 2011; Samuli Suominen <firstname.lastname@example.org> +xv-3.10a-r16.ebuild,
+ Fix building with libpng15 wrt #355883 by Mike Frysinger
Re-opening this bug, since the patch in r16 causes xv to segfault during saving of PNG files, leaving partial files. I have tried this with multiple PNGs. I have masked r16 until we resolve it.
Note that I tried the latest libpng15 as well - still segfaults.
Unable to reproduce that. PNG saving works fine here and also for user called _AxS_.
15 Sep 2011; Samuli Suominen <email@example.com> xv-3.10a-r16.ebuild,
Enchance -libpng15.patch by _AxS_ from Freenode with some bits also from
NetBSD. Restore keywording as libpng15 is about to get unmasked and PNG
saving is working fine here (see bug #355883)
If it still fails for you, masking/keyword dropping is unacceptable and USE="png" will have to be masked in base/package.use.mask instead.