hwc2: set layer color

Test: Add "TARGET_USES_HWC2 := true" to BoardConfig.mk.
      Recompile.
      Run testcases: https://android-review.googlesource.com/#/q/project:
            platform/frameworks/native+branch:master+topic:test-hwc2

Change-Id: Ibaa7c8988d76a03fb9273ac274d43ba4b989fb5c
4 files changed