random.c: fix filling size
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52891 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
random.c: fix filling size
size of element, but the whole size of array.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52891 b2dd03c8-39d4-4d8f-98ff-823fe69b080e