* build/generator/gen_win.py
  Apply some educated guesses on how future Visual Studio versions can be
  supported, given how VS 2010 and VS 2012 bumped their formats.
  Make the regexes a bit stricter.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1452142 13f79535-47bb-0310-9956-ffa450edef68