Adding LIKE range tests for tricky characters U+0425, U+045F, U+2525, U+5F5F.

They have bytes 0x25 and 0x5F. Testing that these bytes are treated as parts
of multi-byte characters rather than underscore and percent sign.

mysql-test/t/ctype_like_range.test

@@ -4,6 +4,8 @@
 --source include/have_utf32.inc
 --source include/have_utf8mb4.inc
 
+SET NAMES utf8;
+
 --disable_warnings
 DROP TABLE IF EXISTS t1;
 DROP VIEW IF EXISTS v1;
@@ -38,6 +40,8 @@ ALTER TABLE t1 MODIFY a VARCHAR(32) CHARACTER SET latin1;
 SELECT * FROM v1;
 
 ALTER TABLE t1 MODIFY a VARCHAR(32) CHARACTER SET utf8;
+INSERT INTO t1 (a) VALUES (_ucs2 0x0425),(_ucs2 0x045F);
+INSERT INTO t1 (a) VALUES (_ucs2 0x2525),(_ucs2 0x5F5F);
 SELECT * FROM v1;
 
 ALTER TABLE t1 MODIFY a VARCHAR(32) CHARACTER SET utf8 COLLATE utf8_unicode_ci;