Remove check of ai.protocol

Solaris 10 returns addrinfo.ai_protocol as 0, not 6.

test/socket/test_addrinfo.rb

@@ -690,7 +690,6 @@ class TestSocketAddrinfo < Test::Unit::TestCase
 
     def test_addrinfo_timeout
       ai = Addrinfo.getaddrinfo("localhost", "ssh", Socket::PF_INET, Socket::SOCK_STREAM, timeout: 1).fetch(0)
-      assert_equal(6, ai.protocol)
       assert_equal(22, ai.ip_port)
     end
   end