array overruns in icheck & dcheck

[Geoffrey Collyer]

V7 icheck and dcheck declare blist and ilist respectively with one
element too few.  Both arrays need an extra element for an end marker.
The effect is that `icheck -b b1 b2 b3 ... b10 filesystem' will dump
core.  Increasing the size of these arrays from NB to NB+1 fixes this
problem.  While you are at it, increase NB from 10 to something like
40, so that an entire track on most disks may be checked at once.

Geoff Collyer, U. of Toronto