Fixed unexpected blocking in async codepaths w/SSL and other issues

[jtrberg]

• unexpected thread blocking in async codepath (https://jira.mariadb.org/browse/CONC-594)
• disabled 0s timeouts not handled correctly
• pvio double free if async connect fails
• invalid usage of 0.0.0.0 IP by test_conc622 to test conn failure. Conn can unexpectedly succeed when server/client are co-located on same host.
• reduced # of iterations of test_conc622

[jtrberg]

I have managed to address issues found in async.c unit test, but I see that there is also a failing test in connection.c:

its called: test_auth256

https://app.travis-ci.com/github/mariadb-corporation/mariadb-connector-c/jobs/592897472

15: Test command: /home/travis/build/mariadb-corporation/mariadb-connector-c/bld/unittest/libmariadb/connection
15: Test timeout computed to be: 180
15: # port: 3305
15: # ssl_port: 3305
15: # socketname: (null)
15: 1..43
15: # TLS server variables
15: # --------------------
15: # have_openssl: YES
15: # have_ssl: YES
15: # performance_schema_show_processlist: OFF
15: # ssl_ca: /etc/sslcert/ca.pem
15: # ssl_capath: 
15: # ssl_cert: /etc/sslcert/server.pem
15: # ssl_cipher: 
15: # ssl_crl: 
15: # ssl_crlpath: 
15: # ssl_key: /etc/sslcert/server.key
15: # Cipher in use: DHE-RSA-AES256-GCM-SHA384
15: # --------------------
15: # Testing against MySQL Server 5.7.40
15: # Host: mariadb.example.com via TCP/IP
15: # Client library: 3.3.4
15: # -------------------------
15: ok 1 - test_status_callback
15: ok 2 - test_conc365
15: ok 3 - test_conc365_reconnect
15: # host: mariadb.example.com
15: # user: boby
15: # cipher: (null)
15: ok 4 - test_conn_str
15: # Cipher in use: DHE-RSA-AES256-GCM-SHA384
15: ok 5 - test_conn_str_1
15: # feature not supported, ed25519 plugin not available
15: ok 6 # skip test_conc544
15: ok 7 - test_conc490
15: ok 8 - test_gtid
15: ok 9 - test_conc496
15: ok 10 # skip test_default_auth
15: ok 11 - test_conc443
15: # feature not supported by MySQL server
15: ok 12 # skip test_conc366
15: # Skip test for non MariaDB server
15: ok 13 - test_conc392
15: # Error: Plugin 'caching_sha2_password' is not loaded
15: # caching_sha256_password not supported
15: ok 14 # skip test_conc312
15: ok 15 - test_conc351
15: # server_status: 16386
15: # server_status after changing autocommit: 16384
15: # server_status after mysql_change_user: 16386
15: ok 16 - test_conc332
15: ok 17 # skip test_conc327
15: ok 18 # skip test_conc317
15: ok 19 # skip test_conc315
15: # error: Your password has expired. To log in you must change it using a client that supports expired passwords.
15: # error: 1820 You must reset your password using ALTER USER statement before executing this statement.
15: ok 20 - test_expired_pw
15: # Cipher in use: DHE-RSA-AES256-GCM-SHA384
15: # Cipher in use: DHE-RSA-AES256-GCM-SHA384
15: ok 21 - test_conc276
15: # character set: latin2
15: ok 22 - test_mdev13100
15: # error: Access denied for user 'sha256user'@'172.18.0.1' (using password: YES)
15: # error: Access denied for user 'sha256user'@'172.18.0.1' (using password: YES)
15: not ok 23 - test_auth256

When I run this test locally on a branch with my changes it passes.