MDEV-16093 Memory leak with triggers

Problem was that blob memory allocated in Table_trigger_list was not
properly freed

mysql-test/r/trigger.result

@@ -2306,4 +2306,15 @@ CREATE TABLE t1 (i INT);
 insert into t2 value (2);
 DROP VIEW v1;
 DROP TABLE t1,t2,t3;
-End of 10.1 tests.
+#
+# MDEV-16093
+# Assertion `global_status_var.global_memory_used == 0' failed or
+# bytes lost after inserting into table with non-null blob and trigger
+#
+CREATE TABLE t1 (b BLOB NOT NULL);
+CREATE TRIGGER tr BEFORE UPDATE ON t1 FOR EACH ROW BEGIN END;
+INSERT INTO t1 VALUES ('foo');
+DROP TABLE t1;
+#
+# End of 10.1 tests.
+#

mysql-test/t/trigger.test

@@ -2656,5 +2656,17 @@ insert into t2 value (2);
 DROP VIEW v1;
 DROP TABLE t1,t2,t3;
 
+--echo #
+--echo # MDEV-16093
+--echo # Assertion `global_status_var.global_memory_used == 0' failed or
+--echo # bytes lost after inserting into table with non-null blob and trigger
+--echo #
+
+CREATE TABLE t1 (b BLOB NOT NULL);
+CREATE TRIGGER tr BEFORE UPDATE ON t1 FOR EACH ROW BEGIN END;
+INSERT INTO t1 VALUES ('foo');
+DROP TABLE t1;
 
---echo End of 10.1 tests.
+--echo #
+--echo # End of 10.1 tests.
+--echo #

sql/sql_trigger.cc

@@ -614,6 +614,7 @@ bool mysql_create_or_drop_trigger(THD *thd, TABLE_LIST *tables, bool create)
 #endif /* WITH_WSREP */
 }
 
+
 /**
   Build stmt_query to write it in the bin-log
   and get the trigger definer.
@@ -1061,6 +1062,11 @@ Table_triggers_list::~Table_triggers_list()
     for (int j= 0; j < (int)TRG_ACTION_MAX; j++)
       delete bodies[i][j];
 
+  /* Free blobs used in insert */
+  if (record0_field)
+    for (Field **fld_ptr= record0_field; *fld_ptr; fld_ptr++)
+      (*fld_ptr)->free();
+
   if (record1_field)
     for (Field **fld_ptr= record1_field; *fld_ptr; fld_ptr++)
       delete *fld_ptr;