Retain configuration change info and sync access.

- If a window was hidden while the configuration changed and then
changed back WindowManagerService would not know that the change
had ever happened and wouldn't notify the window of this. Most
windows wouldn't care but because Keyguard inflates layouts while
it is hidden...

Bug 7094175 fixed?
Bug 7501099 fixed!

Change-Id: If27f5f1d333602dac7719dd39dbdf3fe7954aa06