[PATCH] stop using -1 in syscallent tables

[Denys Vlasenko]

Usage -1 as argument count in syscallent tables
necessitates the check for it, a-la:

        if (tcp->scno >= 0 && tcp->scno < nsyscalls && sysent[tcp->scno].nargs != -1)
                tcp->u_nargs = sysent[tcp->scno].nargs;
        else
                tcp->u_nargs = MAX_ARGS;

which is stupid: we waste cycles checking something which
is constant and known at compile time.

I propose to fix it with these changes:

* Replace all -1 by MA in all tables.
* Redefine struct sysent::nargs as unsigned
(sadly, this is mostly cosmetic, as gcc won't warn
about -1 static initializer for unsigned field, but still...)
* Add #define MA MAX_ARGS / #undef MA around #include "syscallent[N].h"
* Remove sysent[tcp->scno].nargs != -1 checks.

This seems a good plan to me, so I'm going to commit these changes,
but nevertheless feel free to point out any deficiencies in this plan
I might have missed...

-- 
vda