Fix hot reboot in powermenu

Fixes AOSPA-557
Accessing showGlobalActionsDialog() from different threads
(one for broadcasts and one for the actual longpress power button action)
caused a hot reboot when accessing the power menu from quick settings and then from power button.

Change-Id: I4b6efd192404f073c0d1b5655152ae736a398cbd
QuickSwipe: swipe anywhere to flip