Replace deprecated Socket.gethostbyname with Addrinfo.getaddrinfo (#196)

Replace Socket.gethostbyname with Addrinfo.getaddrinfo in FreeBSD test
Addrinfo.getaddrinfo is available since Ruby 1.9

Rubocop warning:

```console
test/fiddle/test_handle.rb:225:7: W: Lint/DeprecatedClassMethods: Socket.gethostbyname is deprecated in favor of Addrinfo.getaddrinfo.
      Socket.gethostbyname("localhost")
      ^^^^^^^^^^^^^^^^^^^^
```

Author: kojix2

test/fiddle/test_handle.rb

@@ -222,7 +222,7 @@ def test_dlerror
       # In general uses of dlerror(3) should call it before use it.
       verbose, $VERBOSE = $VERBOSE, nil
       require 'socket'
-      Socket.gethostbyname("localhost")
+      Addrinfo.getaddrinfo("localhost", nil)
       Fiddle.dlopen("/lib/libc.so.7").sym('strcpy')
     ensure
       $VERBOSE = verbose