Fix for BUG#51716 and BUG#51787: test case improvements.

Split rpl_row_charset into:

  - rpl_row_utf16.
  - rpl_row_utf32.

This way these tests can run independently if server supports
either one of the charsets but not both.

Cleaned up rpl_row_utf32 which had a spurious instruction:
-- let $reset_slave_type_conversions= 0

mysql-test/suite/rpl/r/rpl_row_utf16.result

@@ -0,0 +1,23 @@
+stop slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+reset master;
+reset slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+start slave;
+CREATE TABLE t1(c1 CHAR(10) CHARACTER SET utf16 DEFAULT 'ola');
+INSERT INTO t1 VALUES ('abc');
+INSERT INTO t1 VALUES ();
+#### ON MASTER
+SELECT c1, hex(c1) from t1;
+c1	abc
+hex(c1)	006100620063
+c1	ola
+hex(c1)	006F006C0061
+#### ON SLAVE
+SELECT c1, hex(c1) FROM t1;
+c1	abc
+hex(c1)	006100620063
+c1	ola
+hex(c1)	006F006C0061
+Comparing tables master:test.t1 and slave:test.t1
+DROP TABLE t1;

mysql-test/suite/rpl/r/rpl_row_utf32.result

@@ -23,20 +23,3 @@ DROP TABLE t1;
 SET GLOBAL SLAVE_TYPE_CONVERSIONS= @saved_slave_type_conversions;
 include/stop_slave.inc
 include/start_slave.inc
-CREATE TABLE t1(c1 CHAR(10) CHARACTER SET utf16 DEFAULT 'ola');
-INSERT INTO t1 VALUES ('abc');
-INSERT INTO t1 VALUES ();
-#### ON MASTER
-SELECT c1, hex(c1) from t1; ;
-c1	abc
-hex(c1)	006100620063
-c1	ola
-hex(c1)	006F006C0061
-#### ON SLAVE
-SELECT c1, hex(c1) FROM t1; ;
-c1	abc
-hex(c1)	006100620063
-c1	ola
-hex(c1)	006F006C0061
-Comparing tables master:test.t1 and slave:test.t1
-DROP TABLE t1;

mysql-test/suite/rpl/t/rpl_row_utf16.test

@@ -0,0 +1,26 @@
+-- source include/master-slave.inc
+-- source include/have_binlog_format_row.inc
+-- source include/have_utf16.inc
+
+#
+# BUG#51716: Char column with utf16 character set gives wrong padding on slave
+#
+
+CREATE TABLE t1(c1 CHAR(10) CHARACTER SET utf16 DEFAULT 'ola');
+INSERT INTO t1 VALUES ('abc');  # explicit value is inserted and encoded correctly
+INSERT INTO t1 VALUES ();       # default value is inserted and encoded correctly
+
+-- echo #### ON MASTER
+--query_vertical SELECT c1, hex(c1) from t1
+
+-- sync_slave_with_master
+
+-- echo #### ON SLAVE
+--query_vertical SELECT c1, hex(c1) FROM t1
+
+# assertion: tables don't differ
+-- let $diff_table_1=master:test.t1
+-- let $diff_table_2=slave:test.t1
+-- source include/diff_tables.inc
+
+DROP TABLE t1;

mysql-test/suite/rpl/t/rpl_row_utf32.test

@@ -1,5 +1,6 @@
 -- source include/master-slave.inc
 -- source include/have_binlog_format_row.inc
+-- source include/have_utf32.inc
 
 #
 # BUG#51787 Assertion `(n % 4) == 0' on slave upon INSERT into a table with UTF32
@@ -11,8 +12,6 @@ SET SQL_LOG_BIN=1;
 
 -- connection slave
 
--- let $reset_slave_type_conversions= 0
-
 SET @saved_slave_type_conversions= @@global.slave_type_conversions;
 
 #
@@ -43,26 +42,3 @@ SET GLOBAL SLAVE_TYPE_CONVERSIONS= @saved_slave_type_conversions;
 -- source include/stop_slave.inc
 -- source include/start_slave.inc
 -- connection master
-
-#
-# BUG#51716: Char column with utf16 character set gives wrong padding on slave
-#
-
-CREATE TABLE t1(c1 CHAR(10) CHARACTER SET utf16 DEFAULT 'ola');
-INSERT INTO t1 VALUES ('abc');  # explicit value is inserted and encoded correctly
-INSERT INTO t1 VALUES ();       # default value is inserted and encoded correctly
-
--- echo #### ON MASTER
---query_vertical SELECT c1, hex(c1) from t1; 
-
--- sync_slave_with_master
-
--- echo #### ON SLAVE
---query_vertical SELECT c1, hex(c1) FROM t1; 
-
-# assertion: tables don't differ
--- let $diff_table_1=master:test.t1
--- let $diff_table_2=slave:test.t1
--- source include/diff_tables.inc
-
-DROP TABLE t1;