even when the authentication fails

...otherwise nfid is not valid and do_clunk aborts.

refactor the "write or create file" code into a function (woc_file) to share it with the `put' command.

due to a typo, we end up trying to consume the *expected* amount of qids, but the walk could be shorter.

In particular it's important not to die if the first component can't be walked for any reason!

don't write more than fetched. The code wrote up to sizeof(buf), but it may try to write more than the data sent, which is r (<= sizeof(buf)).

while here also delete the two remaining makefiles from before the -portable merge.