Disable SSL in new libmariadb unless --mysql-ssl=on

The new libmariadb defaults to enabling SSL, which introduces backward
compatibility issues. Moreover, certificate verification may be enforced,
together with SSL, potentially breaking connections with MySQL and older
MariaDB versions.

Thus, disable both certificate validation (apparently there is no option
for it at the moment) and SSL.

Author: vaintroub

cmake/BuildLibmariadb.cmake

@@ -41,7 +41,7 @@ list(APPEND  _EXTRA_CMAKE_ARGS
 ENDIF()
 
 set(LIBMARIADB_GIT_TAG
-    v3.3.11
+    v3.4.2
     CACHE
       STRING
       "Git tag of mariadb client library. Set to empty string to get most recent revision"

src/drivers/mysql/drv_mysql.c

@@ -403,6 +403,11 @@ static int mysql_drv_real_connect(db_mysql_conn_t *db_mysql_con)
 #ifdef HAVE_MYSQL_OPT_SSL_MODE
   DEBUG("mysql_options(%p,%s,%d)", con, "MYSQL_OPT_SSL_MODE", args.ssl_mode);
   mysql_options(con, MYSQL_OPT_SSL_MODE, &args.ssl_mode);
+#else
+  char bool_opt = 0;
+  mysql_options(con, MYSQL_OPT_SSL_VERIFY_SERVER_CERT, &bool_opt);
+  bool_opt = args.use_ssl;
+  mysql_options(con, MYSQL_OPT_SSL_ENFORCE, &bool_opt);
 #endif
 
   if (args.use_ssl)