RFR: JDK-8079087: Add support for Cygwin 2.0

[Erik Joelsson]

Hello,

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