Fix resource copying on non-MSVC targets

cmake/OpenMWMacros.cmake

@@ -172,16 +172,34 @@ macro (openmw_add_executable target)
 	endif (MSVC)
 endmacro (openmw_add_executable)
 
+macro (get_generator_is_multi_config VALUE)
+	if (CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9)
+		set(${VALUE} ${GENERATOR_IS_MULTI_CONFIG})
+	else (CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9)
+		list(LENGTH ${CMAKE_CONFIGURATION_TYPES} ${VALUE})
+	endif ((CMAKE_VERSION VERSION_GREATER 3.9 OR CMAKE_VERSION VERSION_EQUAL 3.9))
+endmacro (get_generator_is_multi_config)
+
 macro (copy_resource_file source_path destination_dir_base dest_path_relative)
-	foreach(cfgtype ${CMAKE_CONFIGURATION_TYPES})
-		configure_file(${source_path} "${destination_dir_base}/${cfgtype}/${dest_path_relative}" COPYONLY)
-	endforeach(cfgtype)
+	get_generator_is_multi_config(multi_config)
+	if (multi_config)
+		foreach(cfgtype ${CMAKE_CONFIGURATION_TYPES})
+			configure_file(${source_path} "${destination_dir_base}/${cfgtype}/${dest_path_relative}" COPYONLY)
+		endforeach(cfgtype)
+	else (multi_config)
+		configure_file(${source_path} "${destination_dir_base}/${dest_path_relative}" COPYONLY)
+	endif (multi_config)
 endmacro (copy_resource_file)
 
 macro (configure_resource_file source_path destination_dir_base dest_path_relative)
-	foreach(cfgtype ${CMAKE_CONFIGURATION_TYPES})
-		configure_file(${source_path} "${destination_dir_base}/${cfgtype}/${dest_path_relative}")
-	endforeach(cfgtype)
+	get_generator_is_multi_config(multi_config)
+	if (multi_config)
+		foreach(cfgtype ${CMAKE_CONFIGURATION_TYPES})
+			configure_file(${source_path} "${destination_dir_base}/${cfgtype}/${dest_path_relative}")
+		endforeach(cfgtype)
+	else (multi_config)
+		configure_file(${source_path} "${destination_dir_base}/${dest_path_relative}")
+	endif (multi_config)
 endmacro (configure_resource_file)
 
 macro (copy_all_resource_files source_dir destination_dir_base destination_dir_relative files)