nftables: Activate link time optimization (LTO)

The ipk sizes for mips_24Kc change like this:
old:
nftables-json_0.9.6-1_mips_24kc.ipk	231.968
nftables-nojson_0.9.6-1_mips_24kc.ipk	204.731

new:
nftables-json_0.9.6-2_mips_24kc.ipk	221.894
nftables-nojson_0.9.6-2_mips_24kc.ipk	193.932

Signed-off-by: Hauke Mehrtens <[email protected]>

package/network/utils/nftables/Makefile

@@ -8,7 +8,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=nftables
 PKG_VERSION:=0.9.6
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
 PKG_SOURCE_URL:=https://netfilter.org/projects/$(PKG_NAME)/files
@@ -58,6 +58,9 @@ ifeq ($(BUILD_VARIANT),json)
   CONFIGURE_ARGS += --with-json
 endif
 
+TARGET_CFLAGS += -flto
+TARGET_LDFLAGS += -flto
+
 define Package/nftables/install/Default
 	$(INSTALL_DIR) $(1)/usr/sbin
 	$(CP) $(PKG_INSTALL_DIR)/usr/sbin/nft $(1)/usr/sbin/