bug#9934: 24.0.91; `region-active-p' definition

[Drew Adams]

> A non-existent region is inactive.

A non-existent region is simply... _not_.
It is not a region, a fortiori not an inactive region.

Or, rather, from false anything follows.

A non-existent region is active.  And inactive.  And red, and president...  It
is a region and not a region.  You can say whatever you like about a
non-existent X, even that it exists!.

If x is an element of the empty set, then <say anything you like, about x or
anything else>.