hex & bit literals are not allowed to follow with UNDERSCORE_CHARSET

[zyguan]

Bug Report

https://github.com/mysql/mysql-server/blob/77306a41670543e103f94fa0db77a71d2b9f88b2/sql/sql_yacc.yy#L13672-L13679

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.

select _utf8 0xD0B1, _utf8 X'D0B1';
select _utf8 0b1101000010110001, _utf8 B'1101000010110001';

2. What did you expect to see?

--------------
select _utf8 0xD0B1, _utf8 X'D0B1'
--------------

+--------------+---------------+
| _utf8 0xD0B1 | _utf8 X'D0B1' |
+--------------+---------------+
| б            | б             |
+--------------+---------------+
--------------
select _utf8 0b1101000010110001, _utf8 B'1101000010110001'
--------------

+--------------------------+---------------------------+
| _utf8 0b1101000010110001 | _utf8 B'1101000010110001' |
+--------------------------+---------------------------+
| б                        | б                         |
+--------------------------+---------------------------+

3. What did you see instead?

ERROR 1064 (42000) at line 1: You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 1 column 19 near "0xD0B1, _utf8 X'D0B1'"

4. What version of TiDB SQL Parser are you using?

master