hwc: HWC 2.0 implementation

Add HWCLayer, HWCCallbacks and implement HWC2 layer functionality.

Change-Id: Ic7764e72f4cae534e68764df4cf80eb3db982071
diff --git a/Android.mk b/Android.mk
index 58146e1..1c16b90 100644
--- a/Android.mk
+++ b/Android.mk
@@ -2,7 +2,7 @@
 display-hals += hdmi_cec
 
 sdm-libs := sdm/libs
-display-hals += $(sdm-libs)/utils $(sdm-libs)/core $(sdm-libs)/hwc
+display-hals += $(sdm-libs)/utils $(sdm-libs)/core $(sdm-libs)/hwc $(sdm-libs)/hwc2
 
 ifeq ($(call is-vendor-board-platform,QCOM),true)
     include $(call all-named-subdir-makefiles,$(display-hals))