Remove static initialization of QObjects

Statically initializing QObjects will cause e.g. the main
thread pointer in QCoreApplication to be set when the library
is loading. On Android, this is never the real main thread.
The effect was a warning about QApplication not being initialized
on main thread, and a race condition which sometimes caused
apps to hang on startup.

[ChangeLog][Android] Fixed possible hang on startup for Qt Quick
applications.

Task-number: QTBUG-36426
Change-Id: I7bd8a8f35ef1a2548949978563e3157f8dc854c7
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Merge remote-tracking branch 'origin/release' into stable

Change-Id: I5ac68cc3ad3926190817f0d3d5b4526e70badff6
Merge "Merge remote-tracking branch 'origin/release' into stable" into refs/staging/stable