MDEV-20923:UBSAN: member access within address … which does not point to an object of type 'xid_count_per_binlog'

Problem:
-------
Accessing a member within 'xid_count_per_binlog' structure results in
following error when 'UBSAN' is enabled.

member access within address 0xXXX which does not point to an object of type
'xid_count_per_binlog'

Analysis:
---------
The problem appears to be that no constructor for 'xid_count_per_binlog' is
being called, and thus the vtable will not be initialized.

Fix:
---
Defined a parameterized constructor for 'xid_count_per_binlog' class.