[nrf fromlist] cmake: Use temp. for edt pickle CMake output

This potentially fixes an issues whereby when sysbuild projects
import dts configuration from images and images are reconfigured,
that sysbuild will needlessly rerun even if the output has not
changed by using a temporary output file and then only updating
the actual file if the contents have changed

Upstream PR #: 96259

Signed-off-by: Jamie McCrae <[email protected]>

Author: nordicjm

cmake/modules/extensions.cmake

@@ -4698,6 +4698,7 @@ function(zephyr_dt_import)
   zephyr_check_arguments_required_all(${CMAKE_CURRENT_FUNCTION} arg ${req_single_args})
 
   set(gen_dts_cmake_script ${ZEPHYR_BASE}/scripts/dts/gen_dts_cmake.py)
+  set(gen_dts_cmake_temp ${arg_EDT_PICKLE_FILE}.cmake.new)
   set(gen_dts_cmake_output ${arg_EDT_PICKLE_FILE}.cmake)
 
   if((${arg_EDT_PICKLE_FILE} IS_NEWER_THAN ${gen_dts_cmake_output}) OR
@@ -4706,11 +4707,13 @@ function(zephyr_dt_import)
     execute_process(
       COMMAND ${PYTHON_EXECUTABLE} ${gen_dts_cmake_script}
       --edt-pickle ${arg_EDT_PICKLE_FILE}
-      --cmake-out ${gen_dts_cmake_output}
+      --cmake-out ${gen_dts_cmake_temp}
       WORKING_DIRECTORY ${PROJECT_BINARY_DIR}
       RESULT_VARIABLE ret
       COMMAND_ERROR_IS_FATAL ANY
     )
+
+    file(COPY_FILE ${gen_dts_cmake_temp} ${gen_dts_cmake_output} ONLY_IF_DIFFERENT)
   endif()
   set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${gen_dts_cmake_script})