iw: compile with LTO enabled

Reduces .ipk size on MIPS from 34k to 33k

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/network/utils/iw/Makefile

@@ -38,11 +38,12 @@ TARGET_CPPFLAGS:= \
 	-I$(STAGING_DIR)/usr/include/libnl-tiny \
 	$(TARGET_CPPFLAGS) \
 	-DCONFIG_LIBNL20 \
-	-D_GNU_SOURCE
+	-D_GNU_SOURCE \
+	-flto
 
 MAKE_FLAGS += \
 	CFLAGS="$(TARGET_CPPFLAGS) $(TARGET_CFLAGS) -ffunction-sections -fdata-sections" \
-	LDFLAGS="$(TARGET_LDFLAGS) -Wl,--gc-sections" \
+	LDFLAGS="$(TARGET_LDFLAGS) -Wl,--gc-sections -flto" \
 	NL1FOUND="" NL2FOUND=Y \
 	NLLIBNAME="libnl-tiny" \
 	LIBS="-lm -lnl-tiny" \