net/udpgso_bench_tx: options to exercise TX CMSG

This enhancement adds options that facilitate load testing with
additional TX CMSG options, and to optionally print results of
various send CMSG operations.

These options are especially useful in isolating situations
where error-queue messages are lost when combined with other
CMSG operations (e.g. SO_ZEROCOPY).

New options:
    -a - count all CMSG messages and match to sent messages
    -T - add TX CMSG that requests TX software timestamps
    -H - similar to -T except request TX hardware timestamps
    -P - call poll() before reading error queue
    -v - print detailed results

v2: Enhancements as per Willem de Bruijn <willemb@google.com>
    - Updated control and buffer parameters for recvmsg
    - poll() parameter cleanup
    - fail on bad audit results
    - remove TOS options
    - improved reporting

v3: Enhancements as per Willem de Bruijn <willemb@google.com>
    - add SOF_TIMESTAMPING_OPT_TSONLY to eliminate MSG_TRUNC
    - general code cleanup
Signed-off-by: Fred Klassen <fklassen@appneta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>