DTrace tcp/udp provider probes

DTrace tcp/udp provider probes

This patch adds DTrace SDT probes for the TCP and UDP protocols.  For tcp
the following probes are added:

tcp:::send		Fires when a tcp segment is transmitted
tcp:::receive		Fires when a tcp segment is received
tcp:::state-change	Fires when a tcp connection changes state
tcp:::connect-request	Fires when a SYN segment is sent
tcp:::connect-refused	Fires when a RST is received for connection attempt
tcp:::connect-established
			Fires when three-way handshake completes for
			initiator

tcp:::accept-refused	Fires when a RST is sent refusing connection attempt
tcp:::accept-established
			Fires when three-way handshake succeeds for acceptor

Arguments for all of these probes are:

arg0	struct sk_buff *; to be translated into pktinfo_t * containing
	implementation-independent packet data
arg1	struct sock *; to be translated into csinfo_t * containing
	implementation-independent connection data
arg2	__dtrace_tcp_void_ip_t *; to be translated into ipinfo_t * containing
	implementation-independent IP information.  Custom type is used as
	this gives DTrace a hint that we can source IP information from other
	arguments if the IP header is not available.
arg3	struct tcp_sock *; to be translated into tcpsinfo_t * containing
	implementation-independent TCP connection data
arg4	struct tcphdr *; to be translated into a tcpinfo_t * containing
	implementation-independent TCP header data
arg5	int representing previous state; to be translated into a
	tcplsinfo_t * which contains the previous state.  Differs from
	current state (arg6) for state-change probes only.
arg6	int representing current state.  Cannot be sourced from struct
	tcp_sock as we sometimes need to probe before state change is
	reflected there
arg7	int representing direction of traffic for probe; values are
	DTRACE_NET_PROBE_INBOUND for receipt of data and
	DTRACE_NET_PROBE_OUTBOUND for transmission.

For udp the following probes are added:

udp:::send		Fires when a udp datagram is sent
udp:::receive		Fires when a udp datagram is received

Arguments for these probes are:

arg0	struct sk_buff *; to be translated into pktinfo_t * containing
        implementation-independent packet data
arg1    struct sock *; to be translated into csinfo_t * containing
        implementation-independent connection data
arg2    void_ip_t *; to be translated into ipinfo_t * containing
        implementation-independent IP information.
arg3	struct udp_sock *; to be translated into a udpsinfo_t * containing
	implementation-independent UDP connection data
arg4	struct udphdr *; to be translated into a udpinfo_t * containing
	implementation-independent UDP header information.

Orabug: 25815197

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Rao Shoaib <rao.shoaib@oracle.com>
Acked-by: Håkon Bugge <haakon.bugge@oracle.com>