[Development] xcode in ci & packaging for Qt5.4.0

[Heikkinen Jani]

Hi all,

QtWebEngine & QtCreator teams has proposed us to update used xcode in packaging & CI machines. At the moment 10.8 mac is using xcode 5.0.2 & 10.9 xcode 5.1.1 . Does someone know any issue why we shouldn't make that update? 
According to our CI guys there were some issues with xcode 5.1 & qt earlier but nowdays at least compiling qt with mac 10.9 & xcode 5.1 seems to work OK (in CI). autotest are at least partially insignificants at the moment in that confiquration...
 
And could following be the rule of the thumb in the future:

we always support only "latest available Xcode for OS X version" with Qt on OS X ?

br,
Jani