* ext/digest/sha2/sha2.c (SHA256_Update, SHA512_Update): avoid Bus
  Error caused by unalignment access on Sparc-Solaris (and possibly on
  other similar environment.) This patch just do memcpy always instead
  of checking architecture. I see no perf drop on my 64bit env. For
  more details, see #4320.

* test/digest/test_digest.rb: add test for unalignment access.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@32547 b2dd03c8-39d4-4d8f-98ff-823fe69b080e