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/libs/gui/IGraphicBufferAlloc.cpp b/libs/gui/IGraphicBufferAlloc.cpp
index d4d4702..ac6ace6 100644
--- a/libs/gui/IGraphicBufferAlloc.cpp
+++ b/libs/gui/IGraphicBufferAlloc.cpp
@@ -101,7 +101,7 @@
             uint32_t height = data.readUint32();
             PixelFormat format = static_cast<PixelFormat>(data.readInt32());
             uint32_t usage = data.readUint32();
-            status_t error;
+            status_t error = NO_ERROR;
             sp<GraphicBuffer> result =
                     createGraphicBuffer(width, height, format, usage, &error);
             reply->writeInt32(error);