code cleanup by @vipulnsward [GH fixes #267]

 * lib/cgi/core.rb: change each to each_value
 * ext/bigdecimal/lib/bigdecimal/{jacobian,math}.rb:
   remove unused variables from bigdecimal lib



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39992 b2dd03c8-39d4-4d8f-98ff-823fe69b080e