much faster than what we have now (sha1.[ch]).  Add a knob
  (--with-bundled-sha1) to extconf.rb which makes it use the
  bundled one anyway.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@2895 b2dd03c8-39d4-4d8f-98ff-823fe69b080e