[tests] Workaround Python 2 “narrow” builds

The so-called Python 2 “narrow” builds support UCS2 only, this is a
workaround to allow unichr to work with any Unicode character in such
builds. This fixes Travis-CI failure as it has narrow Python 2 builds.

Copied from:
https://github.com/behdad/fonttools/blob/master/Lib/fontTools/misc/py23.py
1 file changed