Support for "bits/type_traits.h"

[davide-prade]

I am cross-compiling for ARM architecture with arm-linux-g++ (GCC) 3.4.4 compiler and the standard library header type_traits is under bits folder.
To fix the related compilation issue I have defined the following preprocessor directives, but I think that there is a better way to do the same thing.

#define optional_HAVE_BITS_TYPE_TRAITS  defined(__arm__)

#if optional_HAVE( BITS_TYPE_TRAITS )
# include <bits/type_traits.h>
#elif optional_HAVE( TYPE_TRAITS )
# include <type_traits>
#elif optional_HAVE( TR1_TYPE_TRAITS )
# include <tr1/type_traits>
#endif

[martinmoene]

<type_traits> is a C++11 header. The first GCC compiler to support C++11 seems to be gcc 4.3/4.8 (see bottom of page).

Doesn't seem like a good idea to me to go down this path...