Blender Git Loki

Simple argument to be able to explicitely tell the bitness you want to build Blender in.

python sconsscons.py BF_BITNESS=32
python sconsscons.py BF_BITNESS=64

So from now on for Windows you don't have to run a specific win32 or win64 Python version
to get the Blender version you want. If you omit the BF_BITNESS flag the bitness as per
Python version will be used as before.

Note that this is an argument, so works *only* on the command-line, not in your user-config.py