digest.c: raise exception on init failure

* ext/digest/digest.c: expect digest init and finish functions to
  indicate success or failure; raise exception on failure.
  [ruby-core:61614] [Bug #9659]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46826 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
ext/digest: return values of init and final

* ext/digest: make built-in digest function implementations
  indicate success or failure of init and final functions.
  [ruby-core:61614] [Bug #9659]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46827 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
md5ossl.c: indicate the result

* ext/digest/md5/md5ossl.c: use OpenSSL EVP API instead of MD5 API
  to perform MD5 hashes using OpenSSL in ext/digest.
  [ruby-core:61614] [Bug #9659]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46828 b2dd03c8-39d4-4d8f-98ff-823fe69b080e