The ISO C99 standard (7.18.4) specifies that C++
implementations should define UINT64_C only when
__STDC_CONSTANT_MACROS is defined.
Because we now use UINT64_C in our cpp files (since commit
208bfc49), we need to add this define.
This also solves compilation errors with GCC 4.8.x on ppc64le machines.
v2: add this define to SCons build system
Signed-off-by: Oded Gabbay <firstname.lastname@example.org>
Reviewed-by: Jose Fonseca <email@example.com>