Be sure that {frozen} is defined

Shorewall/Perl/Shorewall/Chains.pm

@@ -690,8 +690,7 @@ sub increment_reference_count( $$ ) {
 #
 # The rules generated by interface options are added to the interfaces's input chain and
 # forward chain. Shorewall::Rules::generate_matrix() may decide to move those rules to
-# a zone-oriented chain, hence this function.
-#
+
 sub move_rules( $$ ) {
     my ($chain1, $chain2 ) = @_;
 
@@ -1011,7 +1010,8 @@ sub new_chain($$)
 		     loglevel   => '',
 		     log        => 1,
 		     cmdlevel   => 0,
-		     references => {} };
+		     references => {},
+		     frozen     => 0 };
 
     trace( $chainref, 'N', undef, '' ) if $debug;