Build the bigfloat library for in-place testing.

def build(python=PYTHON):
    """Build the bigfloat library for in-place testing."""
    clean()
    local(
        "LIBRARY_PATH={library_path} CPATH={include_path} {python} "
        "setup.py build_ext --inplace".format(
            library_path=LIBRARY_PATH,
            include_path=INCLUDE_PATH,
            python=python,
        ))