ex(1) variable name conflict

[Guy Harris]

>	The variable HZ conflicts with a system define in SunOS 4.1
>	(and probably some others).

Probably *many* others, as in "every one that's SVID Issue 2 compliant",
and some that aren't (as in most S5 implementations - given that you're
building this under SunOS 4.1, which has an S5R3.1-based "ex"/"vi", the
reasons why you did so may apply to other systems with S5-flavored
"ex"/"vi" as well).

(SVID Third Edition says you get the units returned by stuff such as the
return value from "times()" by calling "sysconf()", because that's what
POSIX says.)