RFR: JDK-8079087: Add support for Cygwin 2.0

[Tim Bell]

Erik:

Looks good to me.

Tim

> Please review this small patch to configure which enables building on 
> Cygwin 2.0 and newer. Instead of explicitly testing for all versions 
> we know work, I inverted the check to exclude the ones we know won't 
> work. Hitting a known bad Cygwin version should be very rare anyway 
> since 1.7 has been around for a long time now and Cygwin is so 
> aggresive with keeping people updated.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8079087
>
> Patch:
>
> diff -r bc02cff96b92 common/autoconf/basics_windows.m4
> --- a/common/autoconf/basics_windows.m4
> +++ b/common/autoconf/basics_windows.m4
> @@ -320,8 +320,8 @@
>      WINDOWS_ENV_VENDOR='cygwin'
>      WINDOWS_ENV_VERSION="$CYGWIN_VERSION"
>
> -    CYGWIN_VERSION_OK=`$ECHO $CYGWIN_VERSION | $GREP ^1.7.`
> -    if test "x$CYGWIN_VERSION_OK" = x; then
> +    CYGWIN_VERSION_OLD=`$ECHO $CYGWIN_VERSION | $GREP -e '^1\.[0-6]'`
> +    if test "x$CYGWIN_VERSION_OLD" != x; then
>        AC_MSG_NOTICE([Your cygwin is too old. You are running 
> $CYGWIN_VERSION, but at least cygwin 1.7 is required. Please upgrade.])
>        AC_MSG_ERROR([Cannot continue])
>      fi
>
>
> /Erik