hg: build-infra/jdk8: Make a more general hook system for custom autoconf macros.

[magnus.ihse.bursie at oracle.com]

Changeset: 6f468fb121ba
Author:    ihse
Date:      2012-10-24 15:35 +0200
URL:       http://hg.openjdk.java.net/build-infra/jdk8/rev/6f468fb121ba

Make a more general hook system for custom autoconf macros.

! common/autoconf/autogen.sh
! common/autoconf/configure.ac
! common/autoconf/generated-configure.sh