This provides clean up and bug fixes for the RPC layer's TCP socket
connection management logic.  Trond, Alexey, and DaveM have seen this
patch.  i've been running it for several weeks here and feel it is ready
for wider testing.  these two patches are prerequisites for further
clean-ups and fixes for RPC over TCP.

bugs fixed:
+  TCP connection establishment now times out after 60 seconds instead of
   hanging for ten minutes.  60 seconds is more in line with how long a
   server takes to reboot.
+  on a soft-mounted file system, TCP reconnections now time out and fail
   the RPC request, like most other NFS clients, instead of hanging the
   NFS client until the server comes back.
+  on hard-mounted file systems, the RPC layer now delays 15 seconds
   before retrying after a failed connection attempt instead of retrying
   as soon as it can.
+  TCP connection error recovery is now more verbose so users can see why
   their NFS sessions are hung.  this can be tuned with future patches if
   it is unreasonably noisy.
+  the TCP connect logic is cleaned up so adding checks for new errnos
   is easier.
+  the same code now handles both initial connection and reconnection.
   the original initial connection code did not have comprehensive error
   handling.
+  some obscure design elements are now documented in comments.
+  kfree was used by mistake in xprt_destroy.