* lib/securerandom.rb: show actual read length in an error message.

	* lib/securerandom.rb (random_bytes): call to_int method for the
	  argument at first.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@35566 b2dd03c8-39d4-4d8f-98ff-823fe69b080e