checkpatch: indent checks -- stop when we run out of continuation lines

Ensure we terminate when there are no futher continuation lines when
trying to determine relative indent of conditionals and their blocks.
Reported-by: John Daiker <daikerjohn@gmail.com>
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -1547,10 +1547,11 @@ sub process {
 				    $s =~ /^\s*#\s*?/ ||
 				    $s =~ /^\s*$Ident\s*:/) {
 					$continuation = ($s =~ /^.*?\\\n/) ? 1 : 0;
-					$s =~ s/^.*?\n//;
+					if ($s =~ s/^.*?\n//) {
 						$cond_lines++;
 					}
 				}
+			}
 
 			my (undef, $sindent) = line_stats("+" . $s);
 			my $stat_real = raw_line($linenr, $cond_lines);