tests/test-gendoc-sv.t

hghave: enable 'serve' on Windows

I've been using a local hghaveaddon.py to enable this for a couple of months
with reasonable success, and 'killdaemons' is already enabled on Windows.
There's one failure[1] in test-http-proxy.t that this adds, which I can't figure
out.

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-April/096987.html

#require docutils gettext

  $ $TESTDIR/check-gendoc sv
  checking for parse errors