minus zero strikes again

[gwyn at BRL-VLD.ARPA]

From:      Doug Gwyn (VLD/VMB) <gwyn at BRL-VLD.ARPA>

Upon further reflection, I realize that a C implementer on
a 1's-complemenet machine may have made a mistake and
implemented negation (unary minus) by ones'-complementing
the (integer) value instead of correctly subtracting it
from zero, so Henry's query amounts to asking whether any
C implementer on a 1's-complement machine was so foolish.