Testing when a server does not respond to TLS handshake records exposed
a couple of problems, since the daemon would be in SSL_connect() for 6 minutes.

• When the upcall timed out and was retried, the RPCTLS_SYSC_CLSOCKET syscall was broken and did not return an error upon a retry. It allocated a file descriptor for a NULL socket.
• The socket structure in the kernel could be free'd while the daemon was still using it in SSL_connect().
• Adjust the timeout a retry count so that upcalls are only attempted once with a 10minute timeout.

This patch fixes these problems by changing the following:

• If the handshake is in progress, don't soclose(so) in the kernel clnt_vc_destroy().
• Fix the RPCTLS_SYSC_CLSOCKET (and RPCTLS_SYSC_SRVSOCKET) to correctly return an error if the socket is NULL (which means it already has a file decriptor assigned to it).