Fix bug in utils.py when no destination directory is created

This pull request fixes a bug in the copydir function in utils.py. In the `for name in names` block, if no files are copied (e.g. due to filters), then the line `os.makedirs(dst)` is never run. When `shutil.copystat(src, dst)` is run, dst doesn't exist which causes an environment error. If no files are copied due to a filter, the correct behavior should be to return without attempting to create directories or copystat-ing.

I ran into this issue when building against an installation of Qt 4.8.5. The error occurred when trying to copy *.so from the plugins/webkit directory.