This reverts 395641549ac7..536d9e2b9e5b, in particular:
8dffd56936 MDEV-31857 enable MYSQL_OPT_SSL_VERIFY_SERVER_CERT by default
a99570c118 MDEV-31855 SSL cert validation protocol extension
9aa15e72a7 TLS fingerprint
and related commits
* extend the client auth plugin API with a new callback
* relax the plugin version check to allow load a plugin with the
same major version, even if the minor versions differ
* implement the protocol extension:
- don't abort at once if the certificate is self signed and
no CA was explicitly specified
- allow it if it passes fingerprint check
- allow it if plugin has hash_password_bin callback, password was
non-empty and the control hash matches server's
ZSTD compression is now supported for connections
to a MySQL Server 8.0.
Compression algorithms are supported via compression
plugins, which can be found in plugins/compress.
If multiple threads attempt to connect to a server using a
dynamically loaded authentication plugin the error
"plugin is already loaded" might occur. This is caused
by a race condition if one thread waits for a lock to
load the plugin, while another process which obtained the lock
already loaded the plugin.
The API function mysql_load_plugin_v() now returns
the plugin handle (instead of raising an error and returning
a NULL handle) even if the plugin was already loaded.
If the plugin dir wasn't specified via mysql_optionsv() or the
environment variable MARIADB_PLUGIN_DIR wasn't set, the plugin
needs to be read from the default location (current path, DLPATH
or PATH).
