checkpatch: allow commit descriptions on separate line from commit id

The general form for commit id and description is

  'Commit <12+hexdigits> ("commit description/subject line")'

but commit logs often have relatively long commit ids and the commit
description emds on the next line like:

  Some explanation as to why commit <12+hexdigits>
  ("commit foo description/subject line") is improved.

Allow this form.
Signed-off-by: NJoe Perches <joe@perches.com>
Suggested-by: NJoe Lawrence <joe.lawrence@stratus.com>
Tested-by: NJoe Lawrence <joe.lawrence@stratus.com>
Suggested-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2133,7 +2133,10 @@ sub process {
 # Check for improperly formed commit descriptions
 		if ($in_commit_log &&
 		    $line =~ /\bcommit\s+[0-9a-f]{5,}/i &&
-		    $line !~ /\b[Cc]ommit [0-9a-f]{12,40} \("/) {
+		    !($line =~ /\b[Cc]ommit [0-9a-f]{12,40} \("/ ||
+		      ($line =~ /\b[Cc]ommit [0-9a-f]{12,40}\s*$/ &&
+		       defined $rawlines[$linenr] &&
+		       $rawlines[$linenr] =~ /^\s*\("/))) {
 			$line =~ /\b(c)ommit\s+([0-9a-f]{5,})/i;
 			my $init_char = $1;
 			my $orig_commit = lc($2);