- Add a "#error Unsupported target architecture." where needed. A chain of

- Add a "#error Unsupported target architecture." where needed. A chain of
  platform dependent ifdefs is useless if it does not include an error like
  this. You will end up searching for the failure in all the wrong places.
Review URL: http://codereview.chromium.org/150026

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2298 ce2b1a6d-e550-0410-aec6-3dcde31c8c00