Don't set a default value for reSync argument.
Don't set a default value for reSync argument.

- reSync() is only called in ykval-queue,
	and that sets an $older_than argument.

- additionally, the defaults did not match.

- the value in ykval-queue (via ykval-config) is 10 seconds,
	and the value in reSync($older_than=) was 60 seconds.

- no functional change, just makes things less confusing.

Yubico/yubikey-val,Yubico/yubikey-val,Yubico/yubikey-val