Suppressing lint messages on arena_s and exit

[Guy Harris]

>		Warning: (13)  struct/union arena_s never defined
>		warning: possible pointer alignment problem
>		    (9)  	
>
>
>		==============
>		value type declared inconsistently
>		    exit   	llib-lc.brl(50) :: foo.c(10)
>
>...how do I stop the messages about arena_s and exit ?

For "exit", the correct answer is probably "see how it's declared in
'llib-lc.brl', and either 1) fix 'llib-lc.brl' if it's misdeclaring it,
and try again, or 2) declare it that way - which is the proper way - in
'foo.c'."

The SunOS 4.0.3 System V environment "llib-lc" - which is based on the
System V one, which is the one I'd expect IRIX to use - says it returns
"void", i.e. nothing.

As for "arena_s", check if IRIX's "lint" supports a "-z" option. 
Berkeley added that option to "lint" to silence those sorts of
complaints; perhaps SGI picked it up.  (If not, perhaps they should pick
it up.)