hwcomposer: Add HWC_BLIT compositiontype value

- HWC_BLIT this layer will be handled in the HWC, using a blit engine
- setting this will inform Surfaceflinger to flip FB_TARGET

Change-Id: I25d19ec41b57863d451c3e390109c912faf1381c
Merge branch 'kitkat' of https://github.com/AOSPA-legacy/android_hardware_libhardware into HEAD