Ruby

• ext/dl/lib/dl/struct.rb (DL::CUnionEntity::size): Fixed ::size to
  return the size of the union.
• test/dl/test_c_union_entity.rb: Test for DL::CUnionEntity::size

Reviewed by Aaron Patterson

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35848 b2dd03c8-39d4-4d8f-98ff-823fe69b080e