Fix Win32 project generator when swig is not found.
Fix Win32 project generator when swig is not found.

* generator/gen_win.py
  (WinGeneratorBase._find_swig): If swig was not found then setup an
  empty self.swig_libdir so the projects can still be generated.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@849884 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion