checkpatch: add ability to coalesce commit descriptions on multiple lines

If a git commit description is split on consecutive lines, coalesce it
before testing.

This allows:

  commit <foo> ("some long
  description")
Signed-off-by: Joe Perches <joe@perches.com>
Reported-by: Paul Bolle <pebolle@tiscali.nl>
Tested-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2198,6 +2198,13 @@ sub process {
 				 defined $rawlines[$linenr] &&
 				 $rawlines[$linenr] =~ /^\s*\("([^"]+)"\)/) {
 				$orig_desc = $1;
+			} elsif ($line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("[^"]+$/i &&
+				 defined $rawlines[$linenr] &&
+				 $rawlines[$linenr] =~ /^\s*[^"]+"\)/) {
+				$line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("([^"]+)$/i;
+				$orig_desc = $1;
+				$rawlines[$linenr] =~ /^\s*([^"]+)"\)/;
+				$orig_desc .= " " . $1;
 			}
 
 			($id, $description) = git_commit_info($orig_commit,