Propagate systemUiVisibility changes to window manager

The mAttachInfo.mSystemUiVisibility value was changing in
View.dispatchAttachedToWindow but
mAttachInfo.mRecomputeGlobalAttributes was not being set.
Consequently ViewRootImpl.collectViewAttributes was returning
without updating the subtreeSystemUiVisibility. This is fixed
by calling needGlobalAttributesUpdate in dispatchAttachedToWindow.

WIthin ViewRootImpl.collectViewAttributes the assignment to
subtreeSystemUiVisibility was only being made if
mAttachInfo.mSystemUiVisibility was changed within
collectViewAttributes. But mAttachInfo.mSystemUiVisibility
was changing outside of collectViewAttributes in
dispatchAttachedToWindow. Consequently subtreeSystemUiVisibility
was never updated. By looking for a mismatch between
subtreeSystemUiVisibility and mSystemUiVisibility
subtreeSystemUiVisibility gets assigned whenever it is out of
sync.

Fixes bug 7091817.

Change-Id: I1e97a7dec14dc9594876175ae26370fb9030a8a6