Binder: Make binder portable

Changes include
- Binder attempts to cast pointers to a int datatype
  which is not sufficient on a 64-bit platform.

- This patch introduces new read/write functions into
  Parcel that allow pointers to be written using the
  uintptr_t datatype for compile-time data type size
  selection.

-  Change access specifier for the methods above.

-  Binder uses the 64bit android_atomic_release_cas64
   (aka cmpxchg)

Change-Id: I595280541e0ba1d19c94b2ca2127bf9d96efabf1
Signed-off-by: Matthew Leach <matthew.leach@arm.com>
Signed-off-by: Serban Constantinescu <serban.constantinescu@arm.com>