ci: init libfc-sensor-api submodule before building stub

The libfc-sensor-api submodule was not being initialized in CI,
causing the stub library build to fail silently. Use the existing
check_submodules.sh mechanism to ensure the submodule is fetched
before attempting to build, and add RESULT_VARIABLE checks so
cmake configuration and build failures are caught early.

Signed-off-by: Ramon Roche <mrpollo@gmail.com>

boards/modalai/voxl2/cmake/init.cmake

@@ -31,6 +31,12 @@
 #
 ############################################################################
 
+# Initialize libfc-sensor-api submodule (fetches from GitLab if not present)
+execute_process(
+	COMMAND Tools/check_submodules.sh boards/modalai/voxl2/libfc-sensor-api
+	WORKING_DIRECTORY ${PX4_SOURCE_DIR}
+)
+
 include_directories(${PX4_BOARD_DIR}/libfc-sensor-api/inc)
 
 # Build libfc_sensor.so stub library automatically if not already built
@@ -42,9 +48,17 @@ if(NOT EXISTS ${FC_SENSOR_LIB})
 	execute_process(
 		COMMAND ${CMAKE_COMMAND} -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER} ..
 		WORKING_DIRECTORY ${PX4_BOARD_DIR}/libfc-sensor-api/build
+		RESULT_VARIABLE FC_SENSOR_CMAKE_RESULT
 	)
+	if(NOT FC_SENSOR_CMAKE_RESULT EQUAL 0)
+		message(FATAL_ERROR "Failed to configure libfc_sensor stub library")
+	endif()
 	execute_process(
 		COMMAND ${CMAKE_COMMAND} --build .
 		WORKING_DIRECTORY ${PX4_BOARD_DIR}/libfc-sensor-api/build
+		RESULT_VARIABLE FC_SENSOR_BUILD_RESULT
 	)
+	if(NOT FC_SENSOR_BUILD_RESULT EQUAL 0)
+		message(FATAL_ERROR "Failed to build libfc_sensor stub library")
+	endif()
 endif()