[Sheriff] Revert "Sync cygwin version with chromium"

This reverts commit r18392 for breaking python compatibility on windows bots.

BUG=
TBR=yangguo@chromium.org

Review URL: https://codereview.chromium.org/110993006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@18419 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

DEPS

@@ -14,7 +14,7 @@ deps = {
 deps_os = {
   "win": {
     "v8/third_party/cygwin":
-      "http://src.chromium.org/svn/trunk/deps/third_party/cygwin@231940",
+      "http://src.chromium.org/svn/trunk/deps/third_party/cygwin@66844",
 
     "v8/third_party/python_26":
       "http://src.chromium.org/svn/trunk/tools/third_party/python_26@89111",