scmutil: narrow ImportError handling in termwidth()
The array module must exist. It's sufficient to suppress the ImportError of
termios. Also salvaged the comment why we have to handle AttributeError, from
7002bb17cc5e.
# 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