Use QT_HOST_DATA/src to get to the mkspecs.

QT_HOST_DATA/get changed semantic on the dev branch.

Change-Id: I2b190ce011a91144eb8b1731fa58d71d64cd6b17
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Update Info.plist files for new Cocoa main() call pattern

We would get the following error message otherwise, 'No Info.plist
file in application bundle or no NSPrincipalClass in the Info.plist
file, exiting.'

Needed by I790e5138c29aac2e0215a9147d0148fece40ca22.

Change-Id: I8d2301c41e4957195be8ed5da9a55ab5b02c4608
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>