C++11 compatibility.

 * Fix string literal concatenation to not be interpreted as UD
   literals.
 * Add constexpr compatibility for non-integral static members.
 * Use __typeof__ instead of typeof (should become decltype once this
   actually becomes C++11).
 * Add an appropriate cast for atomic_uintptr_t, since moving to C++11
   means moving from <stdatomic.h> to <atomic>, which has better
   typechecking (hooray for not macros!).

Bug: 18466763
Change-Id: I9561dcb2526578687819ff85421ba80d8e1a9694