QCocoaEventDispatcherPrivate members should not be static

QCocoaEventDispatcherPrivate members should not be static

Keep the Cocoa event dispatcher's private data as normal members of
QCocoaEventDispatcherPrivate. This removes the global initializers for
the macTimerHash and cocoaModalSessionStask as well.

To keep timers working, we pass a pointer to the timer's MacTimerInfo
struct to the callback, instead of just the timer id. The MacTimerInfo
needs to keep a pointer back to the QCocoaEventDispatcherPrivate to get
access to the private's members.

Change-Id: Ic3a61e5e1d1d82030735de73cf0b0c70a13c21a4
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@nokia.com>