MDEV-6112 multiple triggers per table

This is similar to MysQL Worklog 3253, but with
a different implementation. The disk format and
SQL syntax is identical with MySQL 5.7.

Fetures supported:
- "Any" ammount of any trigger
- Supports FOLLOWS and PRECEDES to be
  able to put triggers in a certain execution order.

Implementation details:
- Class Trigger added to hold information about a trigger.
  Before this trigger information was stored in a set of lists in
  Table_triggers_list and in Table_triggers_list::bodies
- Each Trigger has a next field that poinst to the next Trigger with the
  same action and time.
- When accessing a trigger, we now always access all linked triggers
- The list are now only used to load and save trigger files.
- MySQL trigger test case (trigger_wl3253) added and we execute these
  identically.
- Even more gracefully handling of wrong trigger files than before. This
  is useful if a trigger file uses functions or syntax not provided by
  the server.
- Each trigger now has a "Created" field that shows when the trigger was
  created, with 2 decimals.

Other comments:
- Many of the changes in test files was done because of the new "Created"
  field in the trigger file. This shows up in SHOW ... TRIGGER and when
  using information_schema.trigger.
- Don't check if all memory is released if on uses --gdb;  This is needed
  to be able to get a list from safemalloc of not freed memory while
  debugging.
- Added option to trim_whitespace() to know how many prefix characters
  was skipped.
- Changed a few ulonglong sql_mode to sql_mode_t, to find some wrong usage
  of sql_mode.

mysql-test/r/trigger_notembedded.result

@@ -133,8 +133,8 @@ INSERT INTO t1 VALUES(6);
 ERROR HY000: The user specified as a definer ('mysqltest_nonexs'@'localhost') does not exist
 SHOW TRIGGERS;
 Trigger	Event	Table	Statement	Timing	Created	sql_mode	Definer	character_set_client	collation_connection	Database Collation
-trg1	INSERT	t1	SET @new_sum = 0	BEFORE	NULL	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	mysqltest_inv@localhost	latin1	latin1_swedish_ci	latin1_swedish_ci
-trg2	INSERT	t1	SET @new_sum = 0	AFTER	NULL	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	mysqltest_nonexs@localhost	latin1	latin1_swedish_ci	latin1_swedish_ci
+trg1	INSERT	t1	SET @new_sum = 0	BEFORE	#	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	mysqltest_inv@localhost	latin1	latin1_swedish_ci	latin1_swedish_ci
+trg2	INSERT	t1	SET @new_sum = 0	AFTER	#	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	mysqltest_nonexs@localhost	latin1	latin1_swedish_ci	latin1_swedish_ci
 DROP TRIGGER trg1;
 DROP TRIGGER trg2;
 CREATE TRIGGER trg1 BEFORE INSERT ON t1
@@ -163,11 +163,11 @@ trg5	@abcdef@@@hostname
 
 SELECT * FROM INFORMATION_SCHEMA.TRIGGERS ORDER BY trigger_name;
 TRIGGER_CATALOG	TRIGGER_SCHEMA	TRIGGER_NAME	EVENT_MANIPULATION	EVENT_OBJECT_CATALOG	EVENT_OBJECT_SCHEMA	EVENT_OBJECT_TABLE	ACTION_ORDER	ACTION_CONDITION	ACTION_STATEMENT	ACTION_ORIENTATION	ACTION_TIMING	ACTION_REFERENCE_OLD_TABLE	ACTION_REFERENCE_NEW_TABLE	ACTION_REFERENCE_OLD_ROW	ACTION_REFERENCE_NEW_ROW	CREATED	SQL_MODE	DEFINER	CHARACTER_SET_CLIENT	COLLATION_CONNECTION	DATABASE_COLLATION
-def	mysqltest_db1	trg1	INSERT	def	mysqltest_db1	t1	0	NULL	SET @a = 1	ROW	BEFORE	NULL	NULL	OLD	NEW	NULL	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION		latin1	latin1_swedish_ci	latin1_swedish_ci
-def	mysqltest_db1	trg2	INSERT	def	mysqltest_db1	t1	0	NULL	SET @a = 2	ROW	AFTER	NULL	NULL	OLD	NEW	NULL	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	@	latin1	latin1_swedish_ci	latin1_swedish_ci
-def	mysqltest_db1	trg3	UPDATE	def	mysqltest_db1	t1	0	NULL	SET @a = 3	ROW	BEFORE	NULL	NULL	OLD	NEW	NULL	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	@abc@def@@%	latin1	latin1_swedish_ci	latin1_swedish_ci
-def	mysqltest_db1	trg4	UPDATE	def	mysqltest_db1	t1	0	NULL	SET @a = 4	ROW	AFTER	NULL	NULL	OLD	NEW	NULL	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	@hostname	latin1	latin1_swedish_ci	latin1_swedish_ci
-def	mysqltest_db1	trg5	DELETE	def	mysqltest_db1	t1	0	NULL	SET @a = 5	ROW	BEFORE	NULL	NULL	OLD	NEW	NULL	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	@abcdef@@@hostname	latin1	latin1_swedish_ci	latin1_swedish_ci
+def	mysqltest_db1	trg1	INSERT	def	mysqltest_db1	t1	1	NULL	SET @a = 1	ROW	BEFORE	NULL	NULL	OLD	NEW	#	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION		latin1	latin1_swedish_ci	latin1_swedish_ci
+def	mysqltest_db1	trg2	INSERT	def	mysqltest_db1	t1	1	NULL	SET @a = 2	ROW	AFTER	NULL	NULL	OLD	NEW	#	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	@	latin1	latin1_swedish_ci	latin1_swedish_ci
+def	mysqltest_db1	trg3	UPDATE	def	mysqltest_db1	t1	1	NULL	SET @a = 3	ROW	BEFORE	NULL	NULL	OLD	NEW	#	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	@abc@def@@%	latin1	latin1_swedish_ci	latin1_swedish_ci
+def	mysqltest_db1	trg4	UPDATE	def	mysqltest_db1	t1	1	NULL	SET @a = 4	ROW	AFTER	NULL	NULL	OLD	NEW	#	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	@hostname	latin1	latin1_swedish_ci	latin1_swedish_ci
+def	mysqltest_db1	trg5	DELETE	def	mysqltest_db1	t1	1	NULL	SET @a = 5	ROW	BEFORE	NULL	NULL	OLD	NEW	#	NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION	@abcdef@@@hostname	latin1	latin1_swedish_ci	latin1_swedish_ci
 connection default;
 DROP USER mysqltest_dfn@localhost;
 DROP USER mysqltest_inv@localhost;