libknc: update XXXrcd comments to highlight remaining work.
libknc: improve debug_printf().
libknc: rename KNC_OPT_NOPRIVATE to KNC_OPT_NOPRIVACY.
libknc: if KNC_SOCK_NONBLOCK then flush before fill on knc_read().
libknc: improve KNC_SOCK_NONBLOCK/KNC_SOCK_CLOEXEC.

We add these to knc_set_opt() and if they are specified, we perform
the appropriate fcntl(2)s to affect the underlying socket.  We
always work on the net socket which we may want to fix in the
[near?] future.
libknc: internal buffering improvements.

	.  knc_put_stream() now uses the internal buffering system via
	   knc_get_istream() rather than always creating a new buffer on
	   each put.

	.  knc_get_istream() now returns MIN(requested, actual).
	   In practice, unless a malloc error occurs, at the moment,
	   we will always return requested---however, in the future,
	   we may decide to return short buffers rather than do
	   what we do now which is simply waste the additional
	   allocation.
libknc: refactor errno handling from knc_{fill,flush}().
libknc: use size_t rather than ssize_t for knc_get_ostream*().
libknc: add preamble to gss errors.
libknc: knc_authenticate() should exit if an error condition exists.
libknc: a bit of help on TCP errors.

We modify knc_{fill,flush} to return errno = EIO if there
is a pending error in the KNC context.

We also mark an EOF read as an error condition as the KNC
session has not been properly terminated with a command
(not implemented, yet...)

We continue if we are in blocking mode and get an EAGAIN---this
should likely be some sort of error as we don't want to busy loop
here, but we'll deal with that later.

And finally, we return errno=EPIPE from knc_write if the socket is
closed.
Add another unit test.
unit.c: improve output and close the fd again (introduced recently.)
libknc: implement knc_fullread().

This is basically netread() for knc.  It will return either the entire
amount requested or an error.  This is useful for various protocols as
knc_read() always reserves the right to return less than the requested
amount.
libknc: testing shows that a very large iovec array is problematic.

So, we limit it.
tests: make unit-simple.c use knc_fullread() in the appropriate places.