configure --with-rsh=CMD and default blocking-IO support

[Martin Pool]

On  6 Feb 2002, Wayne Davison <wayned at users.sourceforge.net> wrote:

> Cool.  I like that one as well.  Here's an implementation.  This patch
> adds the configure option --with(out)-blocking-io and defines a new
> variable that gets put into config.h:  DEFAULT_BLOCKING_IO.

OK, that's good.  Thanks.

> The code now allows the remote shell value to contain a single prefixed
> IO-blocking option.  If the string starts with "--" and it has a space
> in it, the string must start with "--blocking-io ", "--no-blocking-io ",
> or "-- " (the last item allows someone to use a program name that
> matches one of our options -- just for completeness).

I really think we will regret this later.  I don't see any compelling
reason to overload this variable with more than one meaning,
especially because it's only a workaround for an OS/SSH bug.

A general-purpose RSYNC_OPTS variable would be more tasteful.  I think
popt makes supporting this fairly straightforward.  Alternatively
people can use shell functions or scripts.

> and also to not talk like rsh is always the default remote shell.

OK, that's good

-- 
Martin