ROMFS: don't forget to prune rc.board

The startup file rc.board is copied to the build/../genromfs folder
after the pruning of the files happened. Thus, about 2000 bytes of
comments and whitespace were included in the ROMFS.

This commit moves pruning of the files in ROMFS to a separate cmake
custom command which happens after the ROMFS files have been copied and
the extra files have been added.

Testing showed that this change only affected the rc.board file as
expected.

ROMFS/CMakeLists.txt

@@ -70,7 +70,7 @@ endfunction()
 add_subdirectory(${romfs_src_dir})
 
 # directory setup
-# copy all romfs files, process airframes, prune comments
+# copy all romfs files, process airframes
 get_property(romfs_cmake_files GLOBAL PROPERTY PX4_ROMFS_CMAKE_FILES)
 get_property(romfs_copy_files GLOBAL PROPERTY PX4_ROMFS_FILES)
 get_property(module_config_files GLOBAL PROPERTY PX4_MODULE_CONFIG_FILES)
@@ -92,17 +92,14 @@ add_custom_command(OUTPUT ${romfs_gen_root_dir}/init.d/rcS ${romfs_gen_root_dir}
 		--rc-dir ${romfs_gen_root_dir}/init.d
 		--serial-ports ${board_serial_ports} ${added_arguments}
 		--config-files ${module_config_files} #--verbose
-	COMMAND ${PYTHON_EXECUTABLE} ${PX4_SOURCE_DIR}/Tools/px_romfs_pruner.py
-		--folder ${romfs_gen_root_dir} --board ${PX4_BOARD}
 	DEPENDS
 		${jinja_templates}
 		${module_config_files}
 		${romfs_cmake_files}
 		${romfs_copy_files}
 		${PX4_SOURCE_DIR}/Tools/px_process_airframes.py
-		${PX4_SOURCE_DIR}/Tools/px_romfs_pruner.py
 		${PX4_SOURCE_DIR}/Tools/serial/generate_config.py
-	COMMENT "ROMFS: copying, generating airframes, pruning"
+	COMMENT "ROMFS: copying, generating airframes"
 	)
 
 # copy extras into ROMFS
@@ -152,6 +149,17 @@ add_custom_command(OUTPUT romfs_extras.stamp
 	COMMENT "ROMFS: copying extras"
 	)
 
+add_custom_command(OUTPUT romfs_pruned.stamp
+	COMMAND ${PYTHON_EXECUTABLE} ${PX4_SOURCE_DIR}/Tools/px_romfs_pruner.py
+		--folder ${romfs_gen_root_dir} --board ${PX4_BOARD}
+	DEPENDS
+		${romfs_gen_root_dir}/init.d/rcS
+		${romfs_gen_root_dir}/init.d/rc.autostart
+		romfs_extras.stamp
+		${PX4_SOURCE_DIR}/Tools/px_romfs_pruner.py
+	COMMENT "ROMFS: pruning"
+	)
+
 # create romfs.img
 find_program(GENROMFS genromfs)
 if(NOT GENROMFS)
@@ -161,9 +169,7 @@ add_custom_command(OUTPUT romfs.img romfs.txt
 	COMMAND ${CMAKE_COMMAND} -E remove -f romfs.img romfs.txt
 	COMMAND ${GENROMFS} -f romfs.img -d ${romfs_gen_root_dir} -V "NSHInitVol" -v > romfs.txt 2>&1
 	DEPENDS
-		${romfs_gen_root_dir}/init.d/rcS
-		${romfs_gen_root_dir}/init.d/rc.autostart
-		romfs_extras.stamp
+		romfs_pruned.stamp
 	COMMENT "ROMFS: generating image"
 	)