MDEV-20505: Server crash on startup beacuse of bad wsrep configuration

Problem was that if user used bad wsrep configuration we call unireg_abort and in wsrep case there is check to wsrep_server_state that might not yet be initialized. Fixed by checking that wsrep_server_state is initialized before checking it's state. Changes to be committed:	modified: sql/mysqld.cc	modified: sql/wsrep_server_state.h

Author: janlindstrom

sql/mysqld.cc

@@ -1879,6 +1879,7 @@ extern "C" void unireg_abort(int exit_code)
 
 #ifdef WITH_WSREP
  if (WSREP_ON &&
+ Wsrep_server_state::is_inited() &&
  Wsrep_server_state::instance().state() != wsrep::server_state::s_disconnected)
  {
  /*
@@ -5108,6 +5109,7 @@ static int init_server_components()
 
 #ifdef WITH_WSREP
  if (wsrep_init_server()) unireg_abort(1);
+
  if (WSREP_ON && !wsrep_recovery && !opt_abort)
  {
  if (opt_bootstrap) // bootsrap option given - disable wsrep functionality

sql/wsrep_server_state.h

@@ -35,11 +35,17 @@ class Wsrep_server_state : public wsrep::server_state
  const wsrep::gtid& initial_position,
  int max_protocol_version);
  static void destroy();
+
  static Wsrep_server_state& instance()
  {
  return *m_instance;
  }
 
+ static bool is_inited()
+ {
+ return (m_instance != NULL);
+ }
+
  static wsrep::provider& get_provider()
  {
  return instance().provider();