RDS: add debuging code around sock_hold and sock_put.

RDS: add debuging code around sock_hold and sock_put.

RDS had a recent series of memory corruptions because of
a use-after-free and double-free of rds sockets.  This adds
some debugging code around sock_put and sock_hold to
catch any similar bugs and spit out useful debugging info.

This is a temporary commit while customers try out our fix.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Bang Nguyen <bang.nguyen@oracle.com>