Add support of 32-bits and pre-10.7 systems

The sample code is in C++ so "GCC_C_LANGUAGE_STANDARD = gnu99;" is
useless

Do not force the use of 64-bits by removing:
ARCHS = "$(ARCHS_STANDARD_64_BIT)";

Do not force the use of 10.7 or above by removing:
MACOSX_DEPLOYMENT_TARGET = 10.7;

Do not impose any SDK by removing:
SDKROOT = macosx;