Patch to support QPrinter::setCollateCopies() and QPrinter::setDocName() on Mac

Hi,

the attached patch adds support for the PPK_CollateCopies and PPK_DocumentName print engine property keys for the Mac print engine, allowing QPrinter::setCollateCopies() and QPrinter::setDocName() to work properly on Mac OS X. The patch uses Core Printing functions that are available on OSX 10.4 and up, and was generated against a clean snapshot of Qt 4.7.4.
I hope this gets inserted in the upcoming 4.8; shouldn't be a problem as by looking at the git online source browser, the only affected file (src/gui/painting/qprintengine_mac.mm) didn't change at all since 4.7.4...