raddrinfo.c: suppress warnings

* ext/socket/raddrinfo.c (numeric_getaddrinfo): move conditionally
  used variables inside the block, to suppress warnings on platforms
  where inet_pton() is not available.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45146 b2dd03c8-39d4-4d8f-98ff-823fe69b080e