MDEV-18117: Crash with Explain extended when using limit rows examined

No need to set SELECT_LEX:explicit_limit when we have a limit clause
that sets only the EXAMINED ROWS

mysql-test/main/limit_rows_examined.result

@@ -864,3 +864,18 @@ Warnings:
 Warning	1931	Query execution was interrupted. The query examined at least 22 rows, which exceeds LIMIT ROWS EXAMINED (21). The query result may be incomplete
 drop view v;
 drop table t1, t2;
+#
+# MDEV-18117: Crash with Explain extended when using limit rows examined
+#
+create table t1 (c1 char(2));
+create table t2 (c2 char(2));
+insert into t1 values ('bb'), ('cc'), ('aa'), ('dd');
+insert into t2 values ('bb'), ('cc'), ('dd'), ('ff');
+explain extended
+select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	100.00	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	4	100.00	Using where; Using join buffer (flat, BNL join)
+Warnings:
+Note	1003	select `test`.`t1`.`c1` AS `c1`,`test`.`t2`.`c2` AS `c2` from `test`.`t1` join `test`.`t2` where `test`.`t2`.`c2` = `test`.`t1`.`c1`
+drop table t1,t2;

mysql-test/main/limit_rows_examined.test

@@ -576,3 +576,15 @@ EXECUTE ps;
 
 drop view v;
 drop table t1, t2;
+
+--echo #
+--echo # MDEV-18117: Crash with Explain extended when using limit rows examined
+--echo #
+
+create table t1 (c1 char(2));
+create table t2 (c2 char(2));
+insert into t1 values ('bb'), ('cc'), ('aa'), ('dd');
+insert into t2 values ('bb'), ('cc'), ('dd'), ('ff');
+explain extended
+select * from t1, t2 where c1 = c2 LIMIT ROWS EXAMINED 2;
+drop table t1,t2;

sql/sql_yacc.yy

@@ -12653,7 +12653,7 @@ limit_clause:
           {
             $$.select_limit= 0;
             $$.offset_limit= 0;
-            $$.explicit_limit= 1;
+            $$.explicit_limit= 0;
             Lex->set_stmt_unsafe(LEX::BINLOG_STMT_UNSAFE_LIMIT);
           }
         ;