iptables: add ip{,6}tables-legacy{,-restore,-save} symlinks

Now that we can have both legacy and nft iptables variants
installed at the same time, install the legacy symlinks

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

package/network/utils/iptables/Makefile

@@ -614,6 +614,7 @@ endef
 define Package/iptables/install
 	$(INSTALL_DIR) $(1)/usr/sbin
 	$(CP) $(PKG_INSTALL_DIR)/usr/sbin/xtables-legacy-multi $(1)/usr/sbin/
+	$(CP) $(PKG_INSTALL_DIR)/usr/sbin/iptables-legacy{,-restore,-save} $(1)/usr/sbin/
 	$(INSTALL_DIR) $(1)/usr/lib/iptables
 endef
 
@@ -626,6 +627,7 @@ endef
 
 define Package/ip6tables/install
 	$(INSTALL_DIR) $(1)/usr/sbin
+	$(CP) $(PKG_INSTALL_DIR)/usr/sbin/ip6tables-legacy{,-restore,-save} $(1)/usr/sbin/
 endef
 
 define Package/ip6tables-nft/install