Add a test for extension modules in the distutils record file.
Add a test for extension modules in the distutils record file.

I made a note a month ago that install --record wrote incorrect entries
for extension modules (I think the problem was that the first character
of the file was stripped), so I’m now adding a test to try to reproduce
that in the current versions.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator