Replace errs ++ with errs = 1 in handleargs().

errs ++ is a holdover from the CISC days when everything had an
"increment memory" instruction, so errs ++ was smaller than errs = 1.
These days, everything is either x86, whose users obviously consider
some other consideratino more important than code efficiency (or they'd
be using something saner), or RISC, on which errs ++ is usually larger
than errs = 1.