Do not set eTraversalNeeded w/out wake up

Multiple layers may set eTraversalNeeded during Layer->doTransaction.
If a prior layer doesn't wish to wake up SF, setting eTraversalNeeded
may block a later layer from triggering a wake-up.  Set
force transaction instead to trigger doTransaction at a later
time.

Bug: 158409746
Test: build, boot, manual, SurfaceFlinger_test,
libsurfaceflinger_unittest

Change-Id: I6a43eb53323073361c5b1ebe87e4ceb8a6d3f120