Make sure constructors initialize all members

- Add default constructors to Parcelables that didn't have them and
  make sure all members are initialized by the constructors.
- Add missing fields to BufferItem flatten/unflatten.

Change-Id: I9aa83b326dc3aee757762e63be499dc96a74df91
diff --git a/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.h b/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.h
index dc7c355..b46556d 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.h
+++ b/services/surfaceflinger/DisplayHardware/HWC2On1Adapter.h
@@ -247,6 +247,7 @@
                 public:
                     Config(Display& display)
                       : mDisplay(display),
+                        mId(0),
                         mAttributes() {}
 
                     bool isOnDisplay(const Display& display) const {