Removed support for zip from sendfiles. I added it as part of the

sendfiles rewrite, f8baa5a34335fc0fc8ccabfabc601d0af73ab769, a few
weeks ago.  But because sendfiles fed zip from standard input, zip
would use Zip64 extensions.  That would require unzip 6.0 or later
to extract, according to the zip man page.  But current MacOS X
uses unzip 5.52, so it broke there.