Rclone uses directory exclusions to cut down the listing it has to do,
so before this fix `--exclude dir/` would make sure nothing in `dir/`
was scanned, **except** if --fast-list was used, in which case only
the directory was excluded and everything within it was included.
This is rather unexpected, so this patch makes `--exclude dir/` be
equivalent to `--exclude dir/**`, meaning that excluding a directory
excludes it and its contents.
We can't do the same for --include without changing the semantics of
filtering slightly.
Fixes#3375
8897377a54