Add a timeout state to frozen windows

When an activity stops drawing following a rotation the rotation
screenshot would become stuck on top of all the other windows. The
timeout was being acknowledged but mWindowsFreezingScreen was set to
true which kept stopFreezingDisplayLocked() from dismissing the
screen rotation animation.

By changing mWindowsFreezingScreen from a two state variable to a
three state variable, including a timeout state we allow
stopFreezingDisplayLocked() to continue and dismiss the screen
rotation animtion.

This change also reduces the APP_FREEZING_TIMOEOUT from 5 seconds to
2 seconds.

Bug: 15664090

Change-Id: Ida5aca002a82ec8fe1ea99f0ced814c5c8f01a95