tests: correct the remaining fallout from recent path style changes on Windows
Per @martinvonz, `ui.slash` set by the test runner is now capable of playing a
more active role.[1] I verified that both of these work by setting `ui.slash`
to False, but these changes seem cleaner. The problem with check-perf-code.py
was that the proper imports were not being whitelisted due to '\' vs '/'.
[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-February/128701.html
#!/bin/sh
HGENCODING=UTF-8
export HGENCODING
echo ".. -*- coding: utf-8 -*-" > gendoc.txt
echo "" >> gendoc.txt
LANGUAGE=$1 "$PYTHON" "$TESTDIR/../doc/gendoc.py" >> gendoc.txt 2> /dev/null || exit
echo "checking for parse errors"
"$PYTHON" "$TESTDIR/../doc/docchecker" gendoc.txt
"$PYTHON" "$TESTDIR/../doc/runrst" html gendoc.txt /dev/null