Makefile: replace -B with export PYTHONDONTWRITEBYTECODE
Makefile: replace -B with export PYTHONDONTWRITEBYTECODE

So that also stuff like compiletest doesn't produce .pyc files

kervinck/gigatron-rom,kervinck/gigatron-rom,kervinck/gigatron-rom,kervinck/gigatron-rom,kervinck/gigatron-rom,kervinck/gigatron-rom,kervinck/gigatron-rom