dhcp6relay: Save the dbgsym package into the target folder

This makes it possible to install the debug symbols if needed.

Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>

rules/dhcp6relay.mk

@@ -8,3 +8,6 @@ $(SONIC_DHCP6RELAY)_DEPENDS = $(LIBSWSSCOMMON) $(LIBHIREDIS) $(LIBSWSSCOMMON_DEV
 $(DOCKER_DHCP_RELAY)_INSTALL_DEBS = $(LIBSWSSCOMMON) $(LIBHIREDIS) $(LIBSWSSCOMMON_DEV) $(LIBHIREDIS_DEV)
 $(SONIC_DHCP6RELAY)_SRC_PATH = $(SRC_PATH)/$(SONIC_DHCP6RELAY_PKG_NAME)
 SONIC_DPKG_DEBS += $(SONIC_DHCP6RELAY)
+
+SONIC_DHCP6RELAY_DBG = sonic-$(SONIC_DHCP6RELAY_PKG_NAME)-dbgsym_$(SONIC_DHCP6RELAY_VERSION)_$(CONFIGURED_ARCH).deb
+$(eval $(call add_derived_package,$(SONIC_DHCP6RELAY),$(SONIC_DHCP6RELAY_DBG)))