constants.c: fix macro name

* ext/socket/constants.c (rsock_cmsg_type_arg): fix macro name.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40189 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-04-09

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40190 b2dd03c8-39d4-4d8f-98ff-823fe69b080e