We know that event:external will be configured first (because of its
priority). Take advantage of that here in libevent2022 by having it
refuse to configure / politely fail if event:external succeeded.
Also print out some additional lines in configure output indicating
what is going on (i.e., event:external succeeded, so this component
will be skipped, or event:external failed, so this component will be
used).
Signed-off-by: Jeff Squyres <jsquyres@cisco.com>
(cherry picked from commit b063cb6b0f251052dc72d2496e5745ce83d6b869)
6cb3d61dd1