MDEV-24088 Assertion in InnoDB's FTS code may be triggered by a repeated words...

MDEV-24088 Assertion in InnoDB's FTS code may be triggered by a repeated words fed to simple_parser plugin

increment `position` for every word, because the plugin doesn't
(FTS API doesn't use positions that InnoDB FTS relies on)

mysql-test/suite/innodb_fts/r/innodb_fts_plugin.result

@@ -161,6 +161,7 @@ id	title	body
 SELECT COUNT(*) FROM articles;
 COUNT(*)
 5
+INSERT INTO articles (title, body) VALUES ('111', '1234 1234 1234');
 DROP TABLE articles;
 # Test Part 5: Test Uninstall Plugin After Index is Built
 CREATE TABLE articles (

mysql-test/suite/innodb_fts/t/innodb_fts_plugin.test

@@ -158,6 +158,8 @@ SELECT * FROM articles WHERE
 SELECT * FROM articles WHERE
          MATCH(title, body) AGAINST('full text search');
 SELECT COUNT(*) FROM articles;
+
+INSERT INTO articles (title, body) VALUES ('111', '1234 1234 1234');
 DROP TABLE articles;
 
 -- echo # Test Part 5: Test Uninstall Plugin After Index is Built

storage/innobase/fts/fts0fts.cc

@@ -4691,7 +4691,7 @@ fts_tokenize_add_word_for_parser(
 	ut_ad(boolean_info->position >= 0);
 	position = boolean_info->position + fts_param->add_pos;
 	*/
-	position = fts_param->add_pos;
+	position = fts_param->add_pos++;
 
 	fts_add_token(result_doc, str, position);