Bug 1466746 - Debian packages for python-zstandard; r=glandium

python-zstandard's 0.9.1 source distribution contains a debian/
directory.

On Squeeze, producing a Debian package is straightforward.

On Wheezy, we need to hack up Build-Depends because Wheezy doesn't
have a package for the Hypothesis fuzzing library. This package is
only used for testing and our package building disables testing,
so we don't even need to further hack up the packaging to disable
tests.

MozReview-Commit-ID: 6raXjdzggCH