cmake: Register automatic git submodules handling.

micropython.cmake

@@ -1,5 +1,11 @@
 # This file is to be given as "make USER_C_MODULES=..." when building Micropython port
 
+if(ECHO_SUBMODULES)
+    string(CONCAT GIT_SUBMODULES "${GIT_SUBMODULES} " ${CMAKE_CURRENT_LIST_DIR}/lvgl ${CMAKE_CURRENT_LIST_DIR}/pycparser)
+elseif(NOT EXISTS ${CMAKE_CURRENT_LIST_DIR}/lvgl/README.md)
+    message(FATAL_ERROR " lvgl not initialized.\n Run 'make BOARD=${MICROPY_BOARD} submodules'")
+endif()
+
 # Include LVGL component, ignore KCONFIG
 
 idf_build_set_property(LV_MICROPYTHON 1)
@@ -11,7 +17,7 @@ idf_build_set_property(COMPILE_OPTIONS "-Wno-unused-function" APPEND)
 idf_build_set_property(SRCS "${LV_SRC}" APPEND)
 idf_build_set_property(INCLUDE_DIRS "${LV_INCLUDE}" APPEND)
 
-include(${CMAKE_CURRENT_LIST_DIR}/mkrules_usermod.cmake)
+include(${CMAKE_CURRENT_LIST_DIR}/mkrules.cmake)
 
 # Add lv_bindings rules