run-tests: allow specifying an output dir to write .errs to
I'm trying to use run-tests.py on a read-only file system. This series allows
that to happen.
# 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