test-check-code: do not use xargs
We have too many files, and passing them via arguments could cause strange
errors on some platforms [1]. Since check-code.py can now take "-" and read
file names from stdin, use it instead of xargs to avoid the argv size limit.
[1]: https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-April/096346.html
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true