accept_nonblock_spec: IO.select instead of sleep

Waiting on socket I/O using IO.select should work on all platforms.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66646 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/library/socket/tcpserver/accept_nonblock_spec.rb

@@ -18,7 +18,7 @@ describe "Socket::TCPServer.accept_nonblock" do
     }.should raise_error(IO::WaitReadable)
 
     c = TCPSocket.new("127.0.0.1", @port)
-    sleep 0.1
+    IO.select([@server])
     s = @server.accept_nonblock
 
     port, address = Socket.unpack_sockaddr_in(s.getsockname)