hg: build-infra/jdk8: Updated support for building with one full source tree and several small repoes.

[fredrik.ohrstrom at oracle.com]

Changeset: 7754668aa8a6
Author:    ohrstrom
Date:      2012-03-20 13:35 +0100
URL:       http://hg.openjdk.java.net/build-infra/jdk8/rev/7754668aa8a6

Updated support for building with one full source tree and several small repoes.

! common/autoconf/configure
! common/autoconf/configure.ac
! common/autoconf/spec.gmk.in