1. When `ssl_server2` export key functionality fails,
don't exit the server, but reset it, to have the
server recover for next connection.
2. Add text filters for `export keys functionality` test in ssl-opt.sh
to check for additional output, to verify if the export suceeded.
This was discovered in the `ssl-opt.sh` script, where the server exited,
before the test tried to kill the server priocess, resulting in a
`kill: No such process` message.
Fixes#2662
Signed-off-by: Ron Eldor <Ron.Eldor@arm.com>
65d8c2651d