* ext/socket/raddrinfo.c (rsock_unix_sockaddr_len): return
  sizeof(sa_familiy_t) if path is empty.  see "Autobind Feature" in
  unix(7) for details.

* ext/socket/lib/socket.rb (unix_socket_abstract_name?): treat an
  empty path as an abstract name.

* test/socket/test_unix.rb: related test.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38994 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-01-31

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38995 b2dd03c8-39d4-4d8f-98ff-823fe69b080e