rb_digest_base_equal): Simplify the equality check and just
  compare resulted digests since state-level equality should
  not be significant.

* ext/digest/digest.h: Ditto.

* ext/digest/*/*.[ch]: Ditto.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@11131 b2dd03c8-39d4-4d8f-98ff-823fe69b080e