C++11 en Snow Leopard 10.6.8

Estoy tratando de instalar C++11 en 10.6.8, siguiendo esta guía de macports

Desafortunadamente la guía falla cuando llego al paso 7: Reconstruir cctools y ld64 para usar la versión más nueva de llvm:

sudo port -v -n upgrade --force --enforce-variants cctools -llvm34 +llvm40

falla con el mensaje de error:

In file included from /usr/include/limits.h:64:

/usr/include/machine/limits.h:10:2: error: architecture not supported

#error architecture not supported

/usr/include/machine/limits.h es:

/* This is the `system' limits.h, independent of any particular
   compiler.  GCC provides its own limits.h which can be found in
   /usr/lib/gcc, although it is not very informative.
   This file is public domain.  */
#if defined (__i386__) || defined(__x86_64__)
#include 
#elif defined (__arm__)
#include 
#else
#error architecture not supported
#endif

/opt/local/etc/macports/macports.conf contiene:

# CPU architecture to target. Supported values are "ppc", "ppc64",
# "i386", and "x86_64". Defaults to:
# - OS X 10.5 and earlier: "ppc" on PowerPC, otherwise "i386".
# - OS X 10.6 and later: "x86_64" on Intel 64, otherwise "i386".
#build_arch             i386

y

# Space-delimited list of CPU architectures to target when building
# universal. Defaults to "i386 ppc" on Mac OS X 10.5 and earlier,
# "x86_64 i386" on Mac OS X 10.6 through macOS 10.13, and "x86_64" on
# macOS 10.14 and later (the 10.14 SDK is not universal).
#universal_archs        x86_64 i386

¿Alguien tiene un método funcional para instalar C++11 en 10.6.8?