asio coap: If LWIP IPV6 is disabled, automatically don't build asio &…

… coap

- Removes need to manually exclude these components as shown at
  espressif/esp-idf#3781 (comment)

- Hide the config for these components if IPV6 is disabled

- The components are still included in the build, but with no source
  files


* Original commit: espressif/esp-idf@e305f29

components/asio/CMakeLists.txt

@@ -1,3 +1,11 @@
+if(NOT CONFIG_LWIP_IPV6 AND NOT CMAKE_BUILD_EARLY_EXPANSION)
+    # note: the component is still included in the build so it can become visible again in config
+    # without needing to re-run CMake. However no source or header files are built.
+    message(STATUS "IPV6 support is disabled so the asio component will not be built")
+    idf_component_register()
+    return()
+endif()
+
 set(asio_sources "asio/asio/src/asio.cpp")
 
 if(CONFIG_ASIO_SSL_SUPPORT)

components/asio/Kconfig

@@ -1,4 +1,6 @@
 menu "ESP-ASIO"
+    visible if LWIP_IPV6
+
     config ASIO_SSL_SUPPORT
         bool "Enable SSL/TLS support of ASIO"
         default n

components/asio/component.mk

@@ -1,3 +1,5 @@
+ifdef CONFIG_LWIP_IPV6
+
 COMPONENT_ADD_INCLUDEDIRS := asio/asio/include port/include
 COMPONENT_PRIV_INCLUDEDIRS := private_include
 COMPONENT_SRCDIRS := asio/asio/src port/src
@@ -7,3 +9,5 @@ COMPONENT_OBJEXCLUDE := asio/asio/src/asio_ssl.o port/src/esp_asio_openssl_stubs
 endif
 
 COMPONENT_SUBMODULES += asio
+
+endif # CONFIG_LWIP_IPV6