pedantic avoidance of division by zero, likely not actually
possible to hit for real.
ok miod@ jsing@
Remove undocumented _des_crypt() interface and its companion header file,
which had never been installed, so it's unlikely something ever used this
in the last 15~20 years.

ok deraadt@ jsing@ beck@
Define SMALL_REGISTER_BANK on arm and vax, for it generates faster code for
these systems (vax being 30% faster!). (surprisingly, the prime candidate for
SMALL_REGISTER_BANK, SuperH, runs actually slower in that case)
replace malloc(strlen())/strlcpy with strdup

ok beck@ jsing@