Unit tests fail on when running "make test" on for cross-compile

[kpdyer]

We get the following behavior:

$ LD_PRELOAD= make test             
Traceback (most recent call last):
  File "./bin/fteproxy", line 34, in <module>
    import fte
  File "/vagrant/sandbox/fteproxy/fte/__init__.py", line 24, in <module>
    import fte.encoder
  File "/vagrant/sandbox/fteproxy/fte/encoder.py", line 24, in <module>
    import fte.dfa
  File "/vagrant/sandbox/fteproxy/fte/dfa.py", line 24, in <module>
    import fte.cDFA
ImportError: No module named cDFA

[kpdyer]

The issue is simple, we are, under the hood, calling the linux version of python instead of the wine version. So, use the $(PYTHON) env to determine which one we should call.