MDEV-8576: Bootstrap should ignore --enforce-storage-engine option

Allow enforce-storage-engine="" option and use that on mysql_install_db when doing bootstrap.

Author: janlindstrom

scripts/mysql_install_db.pl.in

@@ -428,6 +428,7 @@ my $mysqld_install_cmd_line = quote_options($mysqld_bootstrap,
  "--max_allowed_packet=8M",
  "--default-storage-engine=MyISAM",
  "--net_buffer_length=16K",
+ "--enforce-storage-engine=\"\"",
  @args,
  );
 

scripts/mysql_install_db.sh

@@ -417,7 +417,7 @@ mysqld_bootstrap="${MYSQLD_BOOTSTRAP-$mysqld}"
 mysqld_install_cmd_line()
 {
  "$mysqld_bootstrap" $defaults "$mysqld_opt" --bootstrap \
- "--basedir=$basedir" "--datadir=$ldata" --log-warnings=0 \
+ "--basedir=$basedir" "--datadir=$ldata" --log-warnings=0 --enforce-storage-engine="" \
  $args --max_allowed_packet=8M \
  --net_buffer_length=16K
 }

sql/mysqld.cc

@@ -5293,6 +5293,9 @@ static int init_server_components()
  if (default_tmp_storage_engine && !*default_tmp_storage_engine)
  default_tmp_storage_engine= NULL;
 
+ if (enforced_storage_engine && !*enforced_storage_engine)
+ enforced_storage_engine= NULL;
+
  if (init_default_storage_engine(default_tmp_storage_engine, tmp_table_plugin))
  unireg_abort(1);