Some gnu indent options take negative numbers (e.g. --indent-label).
Add matching for an optional single '-' before the number.
closes: #15754
Signed-off-by: John M Devin <john.m.devin@gmail.com>
Signed-off-by: Doug Kearns <dougkearns@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>