Make Flattenable not virtual

Fallout from the Flattenable change, update all its uses.

Additionnaly, fix/tighten size checks when (un)flatten()ing
things.

Removed the assumption by some flattenables (e.g.: Fence)
that the size passed to them would be exact (it can
and will be larger in some cases)

The code in Parcel is a bit complicated so that we don't
have to expose the full implementation (and also to
keep the code smallish).

Change-Id: I0bf1c8aca2a3128491b4f45510bc46667e566dde
diff --git a/include/ui/Fence.h b/include/ui/Fence.h
index 60156e7..20466b6 100644
--- a/include/ui/Fence.h
+++ b/include/ui/Fence.h
@@ -36,7 +36,7 @@
 // ===========================================================================
 
 class Fence
-    : public LightRefBase<Fence>, public Flattenable
+    : public LightRefBase<Fence>, public Flattenable<Fence>
 {
 public:
     static const sp<Fence> NO_FENCE;
@@ -96,15 +96,13 @@
     // Flattenable interface
     size_t getFlattenedSize() const;
     size_t getFdCount() const;
-    status_t flatten(void* buffer, size_t size,
-            int fds[], size_t count) const;
-    status_t unflatten(void const* buffer, size_t size,
-            int fds[], size_t count);
+    status_t flatten(void*& buffer, size_t& size, int*& fds, size_t& count) const;
+    status_t unflatten(void const*& buffer, size_t& size, int const*& fds, size_t& count);
 
 private:
     // Only allow instantiation using ref counting.
     friend class LightRefBase<Fence>;
-    virtual ~Fence();
+    ~Fence();
 
     // Disallow copying
     Fence(const Fence& rhs);