[CMake] Do copies as a fall-back if symlinks are not available on the platform

There is still a warning issued in that case.

cmake/modules/DuneMacros.cmake

@@ -1228,16 +1228,18 @@ endmacro(dune_symlink_to_source_tree)
 # corresponding build directory. Use for ini files, grid files etc. A warning
 # is issued on Windows systems.
 macro(dune_symlink_to_source_files files)
-  # check for Windwos to issue a warning
-  if(${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
-    if(NOT DEFINED DUNE_WINDOWS_SYMLINK_WARNING)
-      message(WARNING "Your module wanted to create symlinks, but you cannot do that on your platform.")
-      set(DUNE_WINDOWS_SYMLINK_WARNING)
-    endif()
-  else()
-    # create symlinks for all given files
-    foreach(f ${files})
+  # create symlinks for all given files
+  foreach(f ${files})
+    # check for Windows to issue a warning
+    if(${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
+      if(NOT DEFINED DUNE_WINDOWS_SYMLINK_WARNING)
+        message(WARNING "Your module wanted to create symlinks, but you cannot do that on your platform.")
+        set(DUNE_WINDOWS_SYMLINK_WARNING)
+      endif()
+      dune_add_copy_command(${f})
+    else()
+      # create symlink
       execute_process(COMMAND ${CMAKE_COMMAND} "-E" "create_symlink" "${CMAKE_CURRENT_SOURCE_DIR}/${f}" "${CMAKE_CURRENT_BINARY_DIR}/${f}")
-    endforeach()
-  endif()
+    endif()
+  endforeach()
 endmacro(dune_symlink_to_source_files files)