Check for duplicate distinfo items.

PR:		267168
Submitted by:	rodrigo

portlint.pl

@@ -445,6 +445,9 @@ sub checkdistinfo {
 		}
 		if (/(\S+)\s+\((\S+)\)\s+=\s+(\S+)/) {
 			my ($tag, $path, $value) = ($1, $2, $3);
+			if ($records{$path}{$tag}) {
+				&perror("FATAL", $file, $., "duplicate file listed.");
+			}
 			$records{$path}{$tag} = $value;
 
 			if (!$algorithms{$tag} && $tag ne "SIZE") {