Merge changes I1c6a271f,I1e41e5f5,Ib2f48895,Ia8af95d2,Ie966e37d, ...

* changes:
  SF: Fix a couple of Layer ref count issues
  Build SF executable with USE_HWC2 when needed
  HWC2: Clear transform for SolidColor layers
  HWC2: Use SolidColor composition for DimLayer
  HWC2: Kill logspam for non-HWC virtual displays
  HWC2: Fix virtual displays
  HWC2: Don't set null handle for client layers
  HWC2: Hook up to BoardConfig variable
  HWC2: Skip validate/present if display is off