use random port

if port 9999 is in use the tests will fail because the port is hardcoded
I have added a try/catch with Random. It fixes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=755320

Author: hggh

test/internals_test.rb

@@ -359,8 +359,18 @@ def af_family_supported(af)
       begin
         s = Socket.new(af, Socket::SOCK_STREAM, 0)
         begin
-          sa = Socket.pack_sockaddr_in(9999, hosts[af])
-          s.bind(sa)
+          tries = 5
+          begin
+            sa = Socket.pack_sockaddr_in(Random.rand(1024..65000), hosts[af])
+            s.bind(sa)
+          rescue Errno::EADDRINUSE => e
+            tries -= 1
+            if tries > 0
+              retry
+            else
+              raise Errno::EADDRINUSE, e
+            end
+          end
           yield
         rescue Errno::EADDRNOTAVAIL
         ensure