SurfaceFlinger: check transaction timings even if it doesn't have a buffer

Bufferless transactions should also not be applied if they are considered
early.

Bug: 181978893
Test: launch an app and observe systraces
Test: adb shell /data/nativetest64/SurfaceFlinger_test/SurfaceFlinger_test
Change-Id: Ie6cff82f8316c1a299d4c9f151eaf637cb60e154