unarr: stop requiring a patched zlib for Deflate64 support (not much of a speed difference, since the Deflate64 patch to zlib disabled inflate_fast)

git-svn-id: http://sumatrapdf.googlecode.com/svn/trunk/ext/unarr@9598 841c7e00-0c1d-0410-a694-8ba26473ccb1