Bug#19741 segfault with cp1250 charset + like + primary key + 64bit os

LIKE craashed with a pattern having letters in the range 128..255
(e.g. A WITH ACUTE or C WITH CARON) because of wrong cast from
signed char to unsigned int.

mysql-test/r/ctype_cp1250_ch.result

@@ -42,3 +42,11 @@ id	str
 6	aaaaaa
 7	aaaaaaa
 drop table t1;
+set names cp1250;
+create table t1 (a varchar(15) collate cp1250_czech_cs NOT NULL, primary key(a));
+insert into t1 values("abcdefgh");
+insert into t1 values("");
+select a from t1 where a like "abcdefgh";
+a
+abcdefgh
+drop table t1;

mysql-test/t/ctype_cp1250_ch.test

@@ -44,4 +44,14 @@ INSERT INTO t1 VALUES (NULL, 'aaaaaaa');
 select * from t1 where str like 'aa%';
 drop table t1;
 
+#
+# Bug#19741 segfault with cp1250 charset + like + primary key + 64bit os
+#
+set names cp1250;
+create table t1 (a varchar(15) collate cp1250_czech_cs NOT NULL, primary key(a));
+insert into t1 values("abcdefgh");
+insert into t1 values("");
+select a from t1 where a like "abcdefgh";
+drop table t1;
+
 # End of 4.1 tests

strings/ctype-win1250ch.c

@@ -634,11 +634,11 @@ my_like_range_win1250ch(CHARSET_INFO *cs __attribute__((unused)),
       ptr++;					/* Skip escape */
     else if (*ptr == w_one || *ptr == w_many)	/* '_' or '%' in SQL */
       break;
-    *min_str = like_range_prefix_min_win1250ch[(uint)(*ptr)];
+    *min_str = like_range_prefix_min_win1250ch[(uint) (uchar) (*ptr)];
     if (*min_str != min_sort_char)
       only_min_found= 0;
     min_str++;
-    *max_str++ = like_range_prefix_max_win1250ch[(uint)(*ptr)];
+    *max_str++ = like_range_prefix_max_win1250ch[(uint) (uchar) (*ptr)];
   }
 
   *min_length = (uint) (min_str - min_org);