Description:

```--------
After compiling from source, during make test I got the following error:

test main.loaddata failed with error
CURRENT_TEST: main.loaddata
mysqltest: At line 592: query 'LOAD DATA INFILE 'tmpp.txt' INTO TABLE t1
CHARACTER SET ucs2
(@b) SET a=REVERSE(@b)' failed: 1115: Unknown character set: 'ucs2'

I noticed other tests are skipped because of no ucs2
main.mix2_myisam_ucs2                    [ skipped ]  Test requires:'
have_ucs2'

Should main.loaddata be skipped if there is no ucs2

How To Repeat:
```

----------
Run make test on compiled source that doesn't have ucs2

Suggested fix:
-------------
the failing piece of the test should be moved from mysql-test/t/loaddata.test to
mysql-test/t/ctype_ucs.test.

mysql-test/r/ctype_ucs.result

@@ -191,6 +191,32 @@ t1	CREATE TABLE `t1` (
   `r` varchar(10) CHARACTER SET ucs2 NOT NULL DEFAULT ''
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
+#
+# Bug #51876 : crash/memory underrun when loading data with ucs2 
+#   and reverse() function
+#
+# Problem # 1 (original report): wrong parsing of ucs2 data
+SELECT '00' UNION SELECT '10' INTO OUTFILE 'tmpp.txt';
+CREATE TABLE t1(a INT);
+LOAD DATA INFILE 'tmpp.txt' INTO TABLE t1 CHARACTER SET ucs2
+(@b) SET a=REVERSE(@b);
+# should return 2 zeroes (as the value is truncated)
+SELECT * FROM t1;
+a
+0
+1
+DROP TABLE t1;
+# Problem # 2 : if you write and read ucs2 data to a file they're lost
+SELECT '00' UNION SELECT '10' INTO OUTFILE 'tmpp2.txt' CHARACTER SET ucs2;
+CREATE TABLE t1(a INT);
+LOAD DATA INFILE 'tmpp2.txt' INTO TABLE t1 CHARACTER SET ucs2
+(@b) SET a=REVERSE(@b);
+# should return 0 and 1 (10 reversed)
+SELECT * FROM t1;
+a
+0
+1
+DROP TABLE t1;
 create table t2(f1 Char(30));
 insert into t2 values ("103000"), ("22720000"), ("3401200"), ("78000");
 select lpad(f1, 12, "-o-/") from t2;

mysql-test/r/loaddata.result

@@ -533,6 +533,8 @@ a
 1
 DROP TABLE t1;
 #
+
+
 # Bug#11765139  58069: LOAD DATA INFILE: VALGRIND REPORTS INVALID MEMORY READS AND WRITES WITH U
 #
 CREATE TABLE t1(f1 INT);

mysql-test/t/ctype_ucs.test

@@ -68,6 +68,38 @@ RPAD(_ucs2 X'0420',10,_ucs2 X'0421') r;
 SHOW CREATE TABLE t1;
 DROP TABLE t1;
 
+--echo #
+--echo # Bug #51876 : crash/memory underrun when loading data with ucs2 
+--echo #   and reverse() function
+--echo #
+
+--echo # Problem # 1 (original report): wrong parsing of ucs2 data
+SELECT '00' UNION SELECT '10' INTO OUTFILE 'tmpp.txt';
+CREATE TABLE t1(a INT);
+LOAD DATA INFILE 'tmpp.txt' INTO TABLE t1 CHARACTER SET ucs2
+(@b) SET a=REVERSE(@b);
+--echo # should return 2 zeroes (as the value is truncated)
+SELECT * FROM t1;
+
+DROP TABLE t1;
+let $MYSQLD_DATADIR= `select @@datadir`;
+remove_file $MYSQLD_DATADIR/test/tmpp.txt;
+
+
+--echo # Problem # 2 : if you write and read ucs2 data to a file they're lost
+SELECT '00' UNION SELECT '10' INTO OUTFILE 'tmpp2.txt' CHARACTER SET ucs2;
+CREATE TABLE t1(a INT);
+LOAD DATA INFILE 'tmpp2.txt' INTO TABLE t1 CHARACTER SET ucs2
+(@b) SET a=REVERSE(@b);
+--echo # should return 0 and 1 (10 reversed)
+SELECT * FROM t1;
+
+DROP TABLE t1;
+let $MYSQLD_DATADIR= `select @@datadir`;
+remove_file $MYSQLD_DATADIR/test/tmpp2.txt;
+
+
+
 #
 # BUG3946
 #

mysql-test/t/loaddata.test

@@ -570,36 +570,40 @@ DROP TABLE t1;
 connection default;
 disconnect con1;
 
+#############################################################################
+#           The below protion is moved to ctype_ucs.test                    #
+#############################################################################
+#--echo #
+#--echo # Bug #51876 : crash/memory underrun when loading data with ucs2 
+#--echo #   and reverse() function
+#--echo #
+
+#--echo # Problem # 1 (original report): wrong parsing of ucs2 data
+#SELECT '00' UNION SELECT '10' INTO OUTFILE 'tmpp.txt';
+#CREATE TABLE t1(a INT);
+#LOAD DATA INFILE 'tmpp.txt' INTO TABLE t1 CHARACTER SET ucs2
+#(@b) SET a=REVERSE(@b);
+#--echo # should return 2 zeroes (as the value is truncated)
+#SELECT * FROM t1;
+
+#DROP TABLE t1;
+#let $MYSQLD_DATADIR= `select @@datadir`;
+#remove_file $MYSQLD_DATADIR/test/tmpp.txt;
+
+
+#--echo # Problem # 2 : if you write and read ucs2 data to a file they're lost
+#SELECT '00' UNION SELECT '10' INTO OUTFILE 'tmpp2.txt' CHARACTER SET ucs2;
+#CREATE TABLE t1(a INT);
+#LOAD DATA INFILE 'tmpp2.txt' INTO TABLE t1 CHARACTER SET ucs2
+#(@b) SET a=REVERSE(@b);
+#--echo # should return 0 and 1 (10 reversed)
+#SELECT * FROM t1;
+
+#DROP TABLE t1;
+#let $MYSQLD_DATADIR= `select @@datadir`;
+#remove_file $MYSQLD_DATADIR/test/tmpp2.txt;
+######################################################################################
 
---echo #
---echo # Bug #51876 : crash/memory underrun when loading data with ucs2 
---echo #   and reverse() function
---echo #
-
---echo # Problem # 1 (original report): wrong parsing of ucs2 data
-SELECT '00' UNION SELECT '10' INTO OUTFILE 'tmpp.txt';
-CREATE TABLE t1(a INT);
-LOAD DATA INFILE 'tmpp.txt' INTO TABLE t1 CHARACTER SET ucs2
-(@b) SET a=REVERSE(@b);
---echo # should return 2 zeroes (as the value is truncated)
-SELECT * FROM t1;
-
-DROP TABLE t1;
-let $MYSQLD_DATADIR= `select @@datadir`;
-remove_file $MYSQLD_DATADIR/test/tmpp.txt;
-
-
---echo # Problem # 2 : if you write and read ucs2 data to a file they're lost
-SELECT '00' UNION SELECT '10' INTO OUTFILE 'tmpp2.txt' CHARACTER SET ucs2;
-CREATE TABLE t1(a INT);
-LOAD DATA INFILE 'tmpp2.txt' INTO TABLE t1 CHARACTER SET ucs2
-(@b) SET a=REVERSE(@b);
---echo # should return 0 and 1 (10 reversed)
-SELECT * FROM t1;
-
-DROP TABLE t1;
-let $MYSQLD_DATADIR= `select @@datadir`;
-remove_file $MYSQLD_DATADIR/test/tmpp2.txt;
 
 --echo #
 --echo # Bug#11765139  58069: LOAD DATA INFILE: VALGRIND REPORTS INVALID MEMORY READS AND WRITES WITH U