hg: build-infra/jdk8: Add check to make detection that we're running a cygwin make under cygwin

[magnus.ihse.bursie at oracle.com]

Changeset: 3b6670493d2c
Author:    ihse
Date:      2012-10-22 15:12 +0200
URL:       http://hg.openjdk.java.net/build-infra/jdk8/rev/3b6670493d2c

Add check to make detection that we're running a cygwin make under cygwin
and a msys make under msys.

! common/autoconf/basics.m4
! common/autoconf/generated-configure.sh