Fix for bug #7344 (Repeating mysql_server_start/mysql_server_end crash clients)

One more free_charset call added

libmysql/libmysql.c

@@ -186,6 +186,7 @@ void STDCALL mysql_server_end()
   }
   else
     mysql_thread_end();
+  free_charsets();
   mysql_client_init= org_my_init_done= 0;
 }