hash.c: add compact and compact! methods
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56414 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
hash.c: add compact and compact! methods
values from the original hash, to port Active Support behavior.
[Feature #11818]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56414 b2dd03c8-39d4-4d8f-98ff-823fe69b080e