Added cross-compile flags for 32bit Linux
Added cross-compile flags for 32bit Linux

Specified the -m32 GCC flag when using `mode=release32` in SCons.
This will compile a 32bit version of the program so that now I don't
have to boot a 32bit VM everytime! yay!

leouieda/tesseroids-original,leouieda/tesseroids-original,leouieda/tesseroids-original,leouieda/tesseroids-original