i#1096: Fix protect-dstack test on Windows

Updates the hardcoded offsets in the test.

Fixes issue 1096.

Review URL: https://codereview.appspot.com/7448043

git-svn-id: https://dynamorio.googlecode.com/svn/trunk@1956 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6