Replace deprecated mysql_ssl_set() with mysql_options() calls

The helper function mysql_ssl_set() is deprecated since MySQL 8.2, so
use the recommended replacement instead.

The documentation doesn't mention since when are the SSL options
available but it looks like they have been there for sufficiently long
time to not create any problems.

src/backends/mysql/session.cpp

@@ -405,9 +405,27 @@ mysql_session_backend::mysql_session_backend(
     }
     if (ssl_ca_p)
     {
-        mysql_ssl_set(conn_, ssl_key_p ? ssl_key.c_str() : NULL,
-                      ssl_cert_p ? ssl_cert.c_str() : NULL,
-                      ssl_ca.c_str(), 0, 0);
+        if (0 != mysql_options(conn_, MYSQL_OPT_SSL_CA, ssl_ca.c_str()))
+        {
+            clean_up();
+            throw soci_error("mysql_options(MYSQL_OPT_SSL_CA) failed.");
+        }
+    }
+    if (ssl_key_p)
+    {
+        if (0 != mysql_options(conn_, MYSQL_OPT_SSL_KEY, ssl_key.c_str()))
+        {
+            clean_up();
+            throw soci_error("mysql_options(MYSQL_OPT_SSL_KEY) failed.");
+        }
+    }
+    if (ssl_cert_p)
+    {
+        if (0 != mysql_options(conn_, MYSQL_OPT_SSL_CERT, ssl_cert.c_str()))
+        {
+            clean_up();
+            throw soci_error("mysql_options(MYSQL_OPT_SSL_CERT) failed.");
+        }
     }
     if (local_infile_p && local_infile == 1)
     {