Fix compiling pyc files in Python 3.
Fix compiling pyc files in Python 3.

We need to use the build Python, not the conda-build Python.

Fixes #369.

frol/conda-build,frol/conda-build,rmcgibbo/conda-build,shastings517/conda-build,rmcgibbo/conda-build,ilastik/conda-build,mwcraig/conda-build,ilastik/conda-build,dan-blanchard/conda-build,dan-blanchard/conda-build,shastings517/conda-build,rmcgibbo/conda-build,dan-blanchard/conda-build,ilastik/conda-build,mwcraig/conda-build,sandhujasmine/conda-build,shastings517/conda-build,mwcraig/conda-build,sandhujasmine/conda-build,sandhujasmine/conda-build,frol/conda-build