MDEV-29804 Fix SHOW BINLOG EVENTS displaying incorrect session variable values

Query_log_event::pack_info() was displaying inverted values for
foreign_key_checks and unique_checks. The flags
OPTION_NO_FOREIGN_KEY_CHECKS and OPTION_RELAXED_UNIQUE_CHECKS are set
when these checks are *disabled* (i.e., when the user sets them to 0),
but pack_info() was incorrectly printing them as =1. This caused SHOW
BINLOG EVENTS to show foreign_key_checks=1 and unique_checks=1 when
they were actually 0.

Author: tarunw07

mysql-test/suite/binlog/r/binlog_show_binlog_events_session_variables.result

@@ -0,0 +1,7 @@
+set foreign_key_checks= 0, sql_auto_is_null=1, check_constraint_checks=0, unique_checks=0;
+create table t (a int, check(a>1), foreign key(a) references x (x)) engine=InnoDB as select 1 as a;
+include/show_binlog_events.inc
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Gtid	#	#	GTID #-#-#
+master-bin.000001	#	Query	#	#	use `test`; set foreign_key_checks=0, sql_auto_is_null=1, unique_checks=0; create table t (a int, check(a>1), foreign key(a) references x (x)) engine=InnoDB as select 1 as a
+drop table t;

mysql-test/suite/binlog/r/foreign_key.result

@@ -31,4 +31,4 @@ master-bin.000001	#	Table_map	#	#	table_id: # (test.t1)
 master-bin.000001	#	Write_rows_v1	#	#	table_id: # flags: STMT_END_F
 master-bin.000001	#	Xid	#	#	COMMIT /* XID */
 master-bin.000001	#	Gtid	#	#	GTID #-#-#
-master-bin.000001	#	Query	#	#	use `test`; set foreign_key_checks=1; DROP TABLE `t1` /* generated by server */
+master-bin.000001	#	Query	#	#	use `test`; set foreign_key_checks=0; DROP TABLE `t1` /* generated by server */

mysql-test/suite/binlog/t/binlog_show_binlog_events_session_variables.test

@@ -0,0 +1,22 @@
+# ==== Purpose ====
+#
+# Test verifies that reading binary log by using "SHOW BINLOG EVENTS" command
+# from should correctly print the values of session variables such as
+# foreign_key_checks, sql_auto_is_null, unique_checks etc
+#
+# ==== References ====
+#
+# MDEV-29804 SHOW BINLOG EVENTS produces semantically/syntactically incorrect statements
+
+
+--source include/have_log_bin.inc
+--source include/have_innodb.inc
+--source include/have_binlog_format_statement.inc
+ 
+set foreign_key_checks= 0, sql_auto_is_null=1, check_constraint_checks=0, unique_checks=0;
+create table t (a int, check(a>1), foreign key(a) references x (x)) engine=InnoDB as select 1 as a;
+ 
+source include/show_binlog_events.inc;
+ 
+# Cleanup
+drop table t;

mysql-test/suite/rpl/r/rpl_alter_rollback.result

@@ -42,9 +42,9 @@ master-bin.000001	#	Query	#	#	use `test`; alter table t2 add constraint c1 forei
 master-bin.000001	#	Gtid	#	#	GTID #-#-# ROLLBACK ALTER id=#
 master-bin.000001	#	Query	#	#	use `test`; alter table t2 add constraint c1 foreign key (f1) references t1(f1)
 master-bin.000001	#	Gtid	#	#	GTID #-#-# START ALTER
-master-bin.000001	#	Query	#	#	use `test`; set foreign_key_checks=1; alter table t2 add constraint c1 foreign key (f1) references t1(f1)
+master-bin.000001	#	Query	#	#	use `test`; set foreign_key_checks=0; alter table t2 add constraint c1 foreign key (f1) references t1(f1)
 master-bin.000001	#	Gtid	#	#	GTID #-#-# ROLLBACK ALTER id=#
-master-bin.000001	#	Query	#	#	use `test`; set foreign_key_checks=1; alter table t2 add constraint c1 foreign key (f1) references t1(f1)
+master-bin.000001	#	Query	#	#	use `test`; set foreign_key_checks=0; alter table t2 add constraint c1 foreign key (f1) references t1(f1)
 connection slave;
 connection master;
 drop table t2, t1;

sql/log_event_server.cc

@@ -1064,13 +1064,13 @@ void Query_log_event::pack_info(Protocol *protocol)
   {
     buf.append(STRING_WITH_LEN("set "));
     if (flags2 & OPTION_NO_FOREIGN_KEY_CHECKS)
-      buf.append(STRING_WITH_LEN("foreign_key_checks=1, "));
+      buf.append(STRING_WITH_LEN("foreign_key_checks=0, "));
     if (flags2 & OPTION_AUTO_IS_NULL)
-      buf.append(STRING_WITH_LEN("sql_auto_is_null, "));
+      buf.append(STRING_WITH_LEN("sql_auto_is_null=1, "));
     if (flags2 & OPTION_RELAXED_UNIQUE_CHECKS)
-      buf.append(STRING_WITH_LEN("unique_checks=1, "));
+      buf.append(STRING_WITH_LEN("unique_checks=0, "));
     if (flags2 & OPTION_NO_CHECK_CONSTRAINT_CHECKS)
-      buf.append(STRING_WITH_LEN("check_constraint_checks=1, "));
+      buf.append(STRING_WITH_LEN("check_constraint_checks=0, "));
     if (flags2 & OPTION_IF_EXISTS)
       buf.append(STRING_WITH_LEN("@@sql_if_exists=1, "));
     if (flags2 & OPTION_INSERT_HISTORY)