style, sysexits(3), and man RETURN VALUES for sys programs

[tlaronde%polynum.com@localhost]

Rhialto pointed me to sysexits(3) that was exactly what I was looking
for (for inetd(8) revision). So kudos to him!

I'm converting inetd(8) to exiting with conventional values defined
in sysexits(3) since:
	- it auto-documents the code;
	- it allows to script in a consistent manner the return status
	of a sys program;
	- it is a help when tracking a bug since it can point the
	developer at the culprit or at least narrow down what to look for.

So I suggest to add a mention of sysexits(7) to style.

Furthermore, I'm adding a RETURN VALUES section to inetd.8 and I think
it should be standard practice for sys programs.

But I'd like also to request some additions to sysexits(3):

	- a EX_RESOURCES, for an error not in the flow of the program but
	due to a contextual exhaustion of resources (for example allocations
	on the heap---that's the error detected even if there is probably
	another problem elsewhere in this case, except in very small memory
	environments);

	- More fine grained error values for EX_OSERR; specially, error
	for major interfaces---I'd like a EX_KEVENT for example;

BTW, and still concerning style, is there a defined way of generating a
MAN page needing to edit some part of the manual (ex.: usage) depending
on some macros defined or not (in the case of inetd.8---even if this is
not an actual problem because LIBWRAP is always defined---the [-l] flag
depends on the macro; but it is always present in the usage).
-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                     http://www.kergis.com/
                    http://kertex.kergis.com/
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