hg: build-infra/jdk9: Expose compiler version in spec.gmk.

[magnus.ihse.bursie at oracle.com]

Changeset: cfebc332cdbf
Author:    ihse
Date:      2016-02-04 23:47 +0100
URL:       http://hg.openjdk.java.net/build-infra/jdk9/rev/cfebc332cdbf

Expose compiler version in spec.gmk.

! common/autoconf/generated-configure.sh
! common/autoconf/spec.gmk.in
! common/autoconf/toolchain.m4