hg: build-infra/jdk8: * Check cygwin version and disallow other than 1.7.

[magnus.ihse.bursie at oracle.com]

Changeset: eac08f9d5f6e
Author:    ihse
Date:      2012-10-23 15:07 +0200
URL:       http://hg.openjdk.java.net/build-infra/jdk8/rev/eac08f9d5f6e

* Check cygwin version and disallow other than 1.7.
* Print summary information about msys/cygwin, including actual position of root directory.
* Print full Boot JDK version info

! common/autoconf/basics_windows.m4
! common/autoconf/boot-jdk.m4
! common/autoconf/generated-configure.sh
! common/autoconf/help.m4