bug report: start without initial condition

[Mr-2c]

The following if statement does not check whether it has read a header or not and thus uses whatever value the variables have based on the assigned memory. Addition of a simple additional condition (i.e., IF (io==0) THEN...) would fix the issue. https://github.com/davecats/channel/blob/954515c0ce84999589662be6505d44e00206583c/dnsdata.f90#L712