esp32: Restore USER_C_MODULE support with new CMake build system.

Support for User C and C++ modules was lost due to upgrading the esp32 to
the latest CMake based IDF from the GNUMakefile build process.

Restore the support for the esp32 port by integrating with the approach
recently added for the rp2 port.
Signed-off-by: Michael O'Cleirigh <michael.ocleirigh@rivulet.ca>

ports/esp32/Makefile

@@ -18,7 +18,13 @@ GIT_SUBMODULES = lib/berkeley-db-1.xx
 
 .PHONY: all clean deploy erase submodules FORCE
 
-IDFPY_FLAGS += -D MICROPY_BOARD=$(BOARD) -B $(BUILD)
+CMAKE_ARGS =
+
+ifdef USER_C_MODULES
+	CMAKE_ARGS += -DUSER_C_MODULES=${USER_C_MODULES}
+endif
+
+IDFPY_FLAGS += -D MICROPY_BOARD=$(BOARD) -B $(BUILD) $(CMAKE_ARGS)
 
 all:
 	idf.py $(IDFPY_FLAGS) build

ports/esp32/main/CMakeLists.txt

@@ -5,6 +5,10 @@ get_filename_component(MICROPY_DIR ${PROJECT_DIR}/../.. ABSOLUTE)
 include(${MICROPY_DIR}/py/py.cmake)
 include(${MICROPY_DIR}/extmod/extmod.cmake)
 
+if(NOT CMAKE_BUILD_EARLY_EXPANSION)
+    include(${MICROPY_DIR}/py/usermod.cmake)
+endif()
+
 set(MICROPY_QSTRDEFS_PORT
     ${PROJECT_DIR}/qstrdefsport.h
 )
@@ -71,6 +75,7 @@ set(MICROPY_SOURCE_PORT
 set(MICROPY_SOURCE_QSTR
     ${MICROPY_SOURCE_PY}
     ${MICROPY_SOURCE_EXTMOD}
+    ${MICROPY_SOURCE_USERMOD}
     ${MICROPY_SOURCE_LIB}
     ${MICROPY_SOURCE_PORT}
 )
@@ -129,6 +134,7 @@ idf_component_register(
         ${MICROPY_SOURCE_PORT}
     INCLUDE_DIRS
         ${MICROPY_DIR}
+        ${MICROPY_INC_USERMOD}
         ${MICROPY_PORT_DIR}
         ${MICROPY_BOARD_DIR}
         ${CMAKE_BINARY_DIR}
@@ -159,6 +165,10 @@ target_compile_options(${MICROPY_TARGET} PUBLIC
     -Wno-missing-field-initializers
 )
 
+# add usermod
+target_link_libraries(${MICROPY_TARGET} usermod)
+
+
 # Collect all of the include directories and compile definitions for the IDF components.
 foreach(comp ${IDF_COMPONENTS})
     get_target_property(type __idf_${comp} TYPE)