Build open-source lwIP (-llwip_open) as part of normal build.

Makefile

@@ -64,7 +64,7 @@ VENDOR_SDK_DIR_0.9.2 = esp_iot_sdk_v0.9.2
 
 
 
-all: esptool libcirom standalone sdk sdk_patch $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/libhal.a $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc
+all: esptool libcirom standalone sdk sdk_patch $(TOOLCHAIN)/xtensa-lx106-elf/sysroot/usr/lib/libhal.a $(TOOLCHAIN)/bin/xtensa-lx106-elf-gcc lwip
 	@echo
 	@echo "Xtensa toolchain is built, to use it:"
 	@echo
@@ -352,6 +352,7 @@ clean-sdk:
 	rm -rf $(VENDOR_SDK_DIR)
 	rm -f sdk
 	rm -f .sdk_patch_$(VENDOR_SDK)
+	make -C esp-open-lwip -f Makefile.open clean