CMake 2.8.12 and lower allowed the SOURCE signature in add_custom_command

In CMake 3.0 the policy CMP0050 was introduced where it could be set to OLD to keep this behaviour while for NEW an error was raised.
Since CMake 3.5.2 a warning comes up when using the OLD behaviour and that it will be removed in a future version.

In FreeCAD we switched to the new behaviour now and removed the SOURCE signature from add_custom_command which affects the macros
fc_copy_sources, fc_target_copy_resource and fc_target_copy_resource_flat and their usage.
It's not possible any more to add files to a target by using the macros. Now a file must be added to the target before using the macros.

This commit fixes it for Arch, Draft, OpenSCAD, Material, Plot and Ship

cMake/FreeCadMacros.cmake

@@ -15,9 +15,9 @@ MACRO (fc_copy_sources target_name outpath)
 		add_file_dependencies("${infile}" "${outfile}")
 		ADD_CUSTOM_COMMAND(
 			COMMAND   "${CMAKE_COMMAND}" -E copy "${infile}" "${outfile}"
-			TARGET    ${target_name}
-			OUTPUTS   "${outfile}"
+			OUTPUT   "${outfile}"
 			COMMENT "Copying ${infile} to ${outfile}${fc_details}"
+			MAIN_DEPENDENCY "${infile}"
 		)
 	endforeach(it)
 	ADD_CUSTOM_COMMAND(
@@ -49,9 +49,9 @@ MACRO (fc_target_copy_resource target_name inpath outpath)
 		add_file_dependencies("${infile}" "${outfile}")
 		ADD_CUSTOM_COMMAND(
 			COMMAND   "${CMAKE_COMMAND}" -E copy "${infile}" "${outfile}"
-			TARGET    ${target_name}
-			OUTPUTS   "${outfile}"
+			OUTPUT   "${outfile}"
 			COMMENT "Copying ${infile} to ${outfile}${fc_details}"
+			MAIN_DEPENDENCY "${infile}"
 		)
 	endforeach(it)
 	ADD_CUSTOM_COMMAND(