Currently they go in the passt source tree with a fixed names, which means
their presence can mess with subsequent test runs.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

test_iperf3() is a pretty inscrutable mess of nested background processes.
It has a number of ugly sleeps needed to wait for things to complete.

Rewrite it to be cleaner:
  * Use the construct (a & b & wait) to run 'a' and 'b' in parallel, but
    then wait for them both to complete before continuing
  * This allows us to wait for both the server and client to finish, rather
    than sleeping
  * Use jq to do all the math we need to get the final result, rather than
    jq followed by some complicated 'bc' mangling

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

The tests now use a number of pidfiles for qemu and pasta as well as
passt.pid.  Broaden the .gitignore file so these aren't unintentially
committed.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Add the generated README.plain.md file to .gitignore.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

If the tests are interrupted at the right point a passt.pid file can be
left over.  Clean it up with "make clean" and add it to .gitignore so it
doesn't get accidentally committed.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

Ignore various files generated during build or test.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>