This is a follow-up to JDK-8035495 (Improvements in autoconf
integration). It turned out that some of our internal systems are still
calling the configure wrapper (common/autoconf/configure) directly,
instead of the top-level script.
This will change the wrapper so that such usage gets a warning, but not
fail, giving those users time to transition to calling the top-level
entry point instead.
Bug: https://bugs.openjdk.java.net/browse/JDK-8035825
WebRev:
http://cr.openjdk.java.net/~ihse/JDK-8035825-warn-not-fail-when-calling-configure-wrapper/webrev.01
/Magnus
