iproute2: ensure TARGET_CFLAGS are used

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/iproute2/iproute2.mk

@@ -29,13 +29,12 @@ define IPROUTE2_CONFIGURE_CMDS
 	rm -r $(IPROUTE2_DIR)/include/netinet
 	# arpd needs berkeleydb
 	$(SED) "/^TARGETS=/s: arpd : :" $(IPROUTE2_DIR)/misc/Makefile
-	$(SED) "s:-O2:$(TARGET_CFLAGS):" $(IPROUTE2_DIR)/Makefile
 	echo "IPT_LIB_DIR:=/usr/lib/xtables" >>$(IPROUTE2_DIR)/Config
 	$(IPROUTE2_WITH_IPTABLES)
 endef
 
 define IPROUTE2_BUILD_CMDS
-	$(MAKE) CC="$(TARGET_CC)" -C $(@D)
+	$(MAKE) CC="$(TARGET_CC)" CCOPTS="$(TARGET_CFLAGS) -D_GNU_SOURCE" -C $(@D)
 endef
 
 define IPROUTE2_INSTALL_TARGET_CMDS