MINOR: config: Add a warning if tune.chksize is used

This option is now deprecated. It is recent, but it is now marked as
deprecated as far as 2.2. Thus, there is now a warning in the 2.4 if this
option is still used. It will be removed in 2.5.

Becaue the 2.3 is quite new, this patch may be backported to 2.3.
1 file changed