iwinfo: add CPPFLAGS

Add the OpenWrt CPPFLAGS to the FLAGS. iwinfo does not support CPPFLAGS.
This fixes fortify sources support.

Link: https://github.com/openwrt/openwrt/pull/22056
Signed-off-by: Hauke Mehrtens <[email protected]>

package/network/utils/iwinfo/Makefile

@@ -81,7 +81,7 @@ TARGET_CFLAGS += \
 
 MAKE_FLAGS += \
 	FPIC="$(FPIC)" \
-	CFLAGS="$(TARGET_CFLAGS)" \
+	CFLAGS="$(TARGET_CFLAGS) $(TARGET_CPPFLAGS)" \
 	LDFLAGS="$(TARGET_LDFLAGS)" \
 	BACKENDS="nl80211" \
 	SOVERSION="$(IWINFO_ABI_VERSION)"