Fixing versioning.insert and versioning.replace test failes.

Tests started to fail after a merge of MDEV-15107 (from bb-10.2-ext to 10.3),
because MDEV-15107 additionally fixed this problem:
  MDEV-15112 Inconsistent evaluation of spvariable=0 in strict mode

Modifying tests not to reply on the pre-MDEV-15112 behavior.

mysql-test/suite/versioning/common.inc

@@ -53,15 +53,6 @@ begin
   return NULL;
 end~~
 
-create function if not exists current_row(sys_trx_end varbinary(255))
-returns int
-deterministic
-begin
-  declare continue handler for sqlwarning begin end;
-  return sys_trx_end = timestamp'2038-01-19 03:14:07.999999'
-    or sys_trx_end = 18446744073709551615;
-end~~
-
 create function if not exists sys_commit_ts(sys_field varchar(255))
 returns varchar(255)
 deterministic

mysql-test/suite/versioning/common_finish.inc

@@ -5,7 +5,6 @@ drop function default_engine;
 drop function non_default_engine;
 drop function sys_commit_ts;
 drop function sys_datatype;
-drop function current_row;
 drop procedure concat_exec2;
 drop procedure concat_exec3;
 --enable_query_log

mysql-test/suite/versioning/r/insert.result

@@ -331,8 +331,8 @@ c varchar(8),
 period for system_time(s, e))
 with system versioning;
 insert into t1 values (1, null, null, 'foo');
-select i, c, current_row(e) from t1;
-i	c	current_row(e)
+select i, c, e>TIMESTAMP'2038-01-01 00:00:00' AS current_row from t1;
+i	c	current_row
 1	foo	1
 drop table t1;
 drop table t2;

mysql-test/suite/versioning/r/replace.result

 call create_table('t', 'x int');
 insert t values (1, 2);
 replace t values (1, 3);
-select *, current_row(row_end) as current from t for system_time all
+select *, row_end>TIMESTAMP'2038-01-01 00:00:00' as current from t for system_time all
 order by x;
 id	x	current
 1	2	0

mysql-test/suite/versioning/t/insert.test

@@ -225,7 +225,7 @@ create or replace table t1 (
   period for system_time(s, e))
 with system versioning;
 insert into t1 values (1, null, null, 'foo');
-select i, c, current_row(e) from t1;
+select i, c, e>TIMESTAMP'2038-01-01 00:00:00' AS current_row from t1;
 
 drop table t1;
 drop table t2;

mysql-test/suite/versioning/t/replace.test

@@ -6,7 +6,7 @@ call create_table('t', 'x int');
 
 insert t values (1, 2);
 replace t values (1, 3);
-select *, current_row(row_end) as current from t for system_time all
+select *, row_end>TIMESTAMP'2038-01-01 00:00:00' as current from t for system_time all
 order by x;
 
 drop database test;