Update default cachedir to be /var/tmp/cups on Darwin.

Update default cachedir to be /var/tmp/cups on Darwin.

Add coding enumeration and argument to the new httpAssembleURI,
httpAssembleURIf, and httpSeparateURI functions.

Add new cupsBackendDeviceURI() function to get the proper device
URI from a backend (DEVICE_URI env var or argv[0], whichever is
available first)

Add large file compatible httpRead2() and httpWrite2() functions.

Update the previously undocumented ippReadIO and ipp_iocb_t interfaces
to use large file compatible types.

Update the CUPS PPD spec.

Update the OSX test package script some more: don't update/make all, and
add the chmod stuff to the postflight script.

git-svn-id: svn+ssh://src.apple.com/svn/cups/cups.org/trunk@5023 7a7537e8-13f0-0310-91df-b6672ffda945