I missed this tweak in the undo of a prior xattr optimization.
Added a flag to disable xattr hlink optimization.

I added a compatibility flag for protocol 31 that will let both sides
know if they should be using the xattr optimization that attempted to
avoid sending xattr info for hardlinked files.  Since this optimization
was causing some issues, this compatibility flag will ensure that both
sides know if they should be trying to use the optimization or not.
Fix hard-link bugs when receiver isn't capable.

If the receiving side cannot hard-link symlinks and/or special files
(including devices) then we now properly handle incoming hard-linked
items (creating separate identical items).
Put zlib and popt -I options early in the CFLAGS.
Updated NEWS & tweaked a comment.
Make sure cmp_time() doesn't mess up due to a time_t overflow.
Fixes bug 10643.
Make sure the link() destination file doesn't exist.
Add a clarification about shell wildcard expansion.
Preparing for release of 3.1.1