rssileds: Fix build with external toolchains

Pass down TARGET_CPPFLAGS for path to header files, and append the
libraries we depend on in TARGET_LDFLAGS. Put TARGET_LDFLAGS at the end
of the command line as is required by modern GCC/binutils.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

package/network/utils/rssileds/Makefile

@@ -29,9 +29,11 @@ endef
 define Build/Configure
 endef
 
+TARGET_LDFLAGS += -liwinfo -luci -lubox -lnl-tiny
+
 define Build/Compile
-	$(TARGET_CC) $(TARGET_CFLAGS) -Wall -liwinfo \
-		-o $(PKG_BUILD_DIR)/rssileds $(PKG_BUILD_DIR)/rssileds.c
+	$(TARGET_CC) $(TARGET_CFLAGS) $(TARGET_CPPFLAGS) -Wall \
+		-o $(PKG_BUILD_DIR)/rssileds $(PKG_BUILD_DIR)/rssileds.c $(TARGET_LDFLAGS)
 endef
 
 define Package/rssileds/install