death of nargs(3)

[Doug Gwyn]

It is perhaps also worth pointing out that nargs() didn't really return
the number of arguments, just the number of words on the stack used for
arguments.  As C grew, this became less sensible.

I can easily enough imagine a reasonable implementation of C for which
requiring that something like nargs() work would force a slower function
call interface, which would be a poor trade-off.