utils: checkstyle.py: Support single line hunks

The checkstyle script expects hunks to be declared with a start line and
line count, however the unified diff format [0] declares that a single
line hunk will only have the start line:

> If a hunk contains just one line, only its start line number appears.
> Otherwise its line numbers look like ‘start,count’. An empty hunk is
> considered to start at the line that follows the hunk.

[0] https://www.gnu.org/software/diffutils/manual/html_node/Detailed-Unified.html#Detailed-Unified

Attempting to parse a single line hunk results in the following error:

  File "./utils/checkstyle.py", line 110, in __init__
    raise RuntimeError("Malformed diff hunk header '%s'" % line)
  RuntimeError: Malformed diff hunk header '@@ -1 +1,2 @@

The DiffHunk class only makes use of the start line, and does not
utilise the line count, thus update the regex to make the unused
groups optional.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

0 files changed, 0 insertions, 0 deletions