Added the client rsync-ssl script and various client/daemon support
files needed for talking to an rsync daemon over SSL on port 874 (no
tls support).  This uses an elegant stunnel setup that was detailed
by dozzie (see the resources page) now that stunnel4 has improved
command-spawning support.  Also incorporates some tweaks by devzero
(e.g. the nice no-tmpfile-config client-side code) and a few by me
(including logging of the actual remote IP that came in to the
stunnel process).  This probably still needs a little work.

Fixes bug 8838.

Fixes bug 9882.

The cleanup code will try to flush the output buffer in some
circumstances, which is not valid if we're handling an async signal
(since it might have interrupted some partial I/O in the main thread).
These signals now set a flag and try to let the main I/O handler take
care of the exit strategy.  Fixes a protocol error that could happen
when trying to exit after a kill signal.

- If iconv() returns EINVAL or EILSEQ and the error is being ignored, make
  sure that there is room in the output buffer to store the erroneous char.
- When accepting an erroneous char, be sure to break if there are no more
  input characters (without calling iconv() with a zero input length).

- Avoid relinking a file that is already linked correctly.
- Avoid trashing the stat buffer of an existing file in try_dests_reg().

when the dest file is unlinked and the hard link fails.

Fixes bug #5644.

Fixes bug 9212.