make it a little easier to read and a little more optimized.  Also
made the flag size in our function calls match the size of the flags
in the flist_struct.  These changes will make it easier for me to
optimize the sending of the hard-link data in a future commit.

- The realloc in init_hard_links() might fail if the list is empty
  (which can happen if there are no regular files in the transfer).
  I changed the code to free the list in that case.

match hlink_compare()

file_struct instead of a copy of the file_struct list.

systems (reported by Jay Fenlason).

a "struct file_list *", which allows us to call it with a copy of the
current file_struct entry that we've modified.  This is better than
modifying the entry directly because the latter causes the shared
memory between the generator and the receiver to slowly vanish as
the in-memory changes happen.

SunOS systems (and I hope the former works -- we'll see).

with the variables in the code that manipulates these values.

patch by Bardur Arantsson.

with autoconf 2.58 and above.

implements listening on multiple addresses and a fix for IPv6-only
systems.

non-root, and to ignore a gid of -1.

current file received some literal data yet or not.