Revision 321061

- png_memcpy is now part of libpng private API,
  replace it with memcpy.
- Pet portlint (trim Makefile header, remove ABI version on LIB_DEPENDS).

PR:		ports/172377
Submitted by:	Michael Curtis <michael@moltenmercury.org>
Approved by:	Mark Atkinson <atkin901@gmail.com> (maintainer)