Merge branch 'bpf-samples-sockmap-improvements'

John Fastabend says:

====================
The sockmap sample is pretty simple at the moment. All it does is open
a few sockets attach BPF programs/sockmaps and sends a few packets.

However, for testing and debugging I wanted to have more control over
the sendmsg format and data than provided by tools like iperf3/netperf,
etc. The reason is for testing BPF programs and stream parser it is
helpful to be able submit multiple sendmsg calls with different msg
layouts. For example lots of 1B iovs or a single large MB of data, etc.

Additionally, my current test setup requires an entire orchestration
layer (cilium) to run. As well as lighttpd and http traffic generators
or for kafka testing brokers and clients. This makes it a bit more
difficult when doing performance optimizations to incrementally test
small changes and come up with performance delta's and perf numbers.

By adding a few more options and an additional few tests the sockmap
sample program can show a more complete example and do some of the
above. Because the sample program is self contained it doesn't require
additional infrastructure to run either.

This series, although still fairly crude, does provide some nice
additions. They are

  - a new sendmsg tests with a sender and recv threads
  - a new base tests so we can get metrics/data without BPF
  - multiple GBps of throughput on base and sendmsg tests
  - automatically set rlimit and common variables

That said the UI is still primitive, more features could be added,
more tests might be useful, the reporting is bare bones, etc. But,
IMO lets push this now rather than sit on it for weeks until I get
time to do the above improvements. Additional patches can address
the other limitations/issues. Another thing I am considering is
moving this into selftests, after a few more fixes so we avoid
false failures, so that we get more sockmap testing.

v2: removed bogus file added by patch 3/7
v3: 1/7 replace goto out with returns, remove sighandler update,
    2/7 free iov in error cases
    3/7 fix bogus makefile change, bail out early on errors
v4: add Martin's "nits" and ACKs along with fixes to 2/7 iov free
    also pointed out by Martin.

Thanks Daniel and Martin for the reviews!
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>