fatbuild fixes: - A change to define CXX in fatbuild, which comforts the configure script a little, even if we don't use C++ anywhere. - Some code to see how many CPU cores exist and parallelize make across them. - CFLAGS that apply to both archs are specified seperately (-O3, -pipe, etc) - -fvisibility=hidden for the gcc4 builds - a "clean", "clean-ppc" and "clean-x86" command - Fix to SDL_config_macosx.h for the HAVE_ALLOCA_H thing. Now builds on an Intel Mac.