MDEV-25047: SIGSEGV in mach_read_from_n_little_endian

Virtual column fields are not found in prebuilt data type, so we should
match InnoDB fields with `get_innobase_type_from_mysql_type` method.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

mysql-test/suite/galera/r/galera_virtual_blob.result

+CREATE TABLE t (f INT GENERATED ALWAYS AS (a+b)VIRTUAL,a INT,b INT,h BLOB);
+INSERT INTO t (a,b)VALUES(0,0), (0,0), (0,0), (0,0), (0,0);
+SELECT * from t;
+f	a	b	h
+0	0	0	NULL
+0	0	0	NULL
+0	0	0	NULL
+0	0	0	NULL
+0	0	0	NULL
+connection node_2;
+SELECT * from t;
+f	a	b	h
+0	0	0	NULL
+0	0	0	NULL
+0	0	0	NULL
+0	0	0	NULL
+0	0	0	NULL
+connection node_1;
+DROP TABLE t;

mysql-test/suite/galera/t/galera_virtual_blob.test

+--source include/galera_cluster.inc
+
+CREATE TABLE t (f INT GENERATED ALWAYS AS (a+b)VIRTUAL,a INT,b INT,h BLOB);
+INSERT INTO t (a,b)VALUES(0,0), (0,0), (0,0), (0,0), (0,0);
+SELECT * from t;
+
+--connection node_2
+SELECT * from t;
+--connection node_1
+DROP TABLE t;

storage/innobase/handler/ha_innodb.cc

@@ -8874,6 +8874,8 @@ wsrep_calc_row_hash(
 	for (uint i = 0; i < table->s->fields; i++) {
 		byte null_byte=0;
 		byte true_byte=1;
+		ulint col_type;
+		ulint is_unsigned;
 
 		const Field* field = table->field[i];
 		if (!field->stored_in_db()) {
@@ -8882,8 +8884,9 @@ wsrep_calc_row_hash(
 
 		ptr = (const byte*) row + get_field_offset(table, field);
 		len = field->pack_length();
+		col_type = get_innobase_type_from_mysql_type(&is_unsigned, field);
 
-		switch (prebuilt->table->cols[i].mtype) {
+		switch (col_type) {
 
 		case DATA_BLOB:
 			ptr = row_mysql_read_blob_ref(&len, ptr, len);