[cfe-dev] Feature-test macro whether compiling against libc++abi?

[Stephan Bergmann via cfe-dev]

Is there some sort of feature-test macro that client code can use to 
determine whether it is being compiled against libc++abi?

I see that there is

   #define _LIBCPPABI_VERSION 1002

in the libc++abi-provided cxxabi.h.  It would apparently happen to help 
tell libc++abi from libstdc++/libsupc++ (where _LIBCPPABI_VERSION is 
left undefined after #include <cxxabi.h>), but I'm not sure whether 
that's by design or by accident?