Reworked the error handling of non-blocking reads and writes.

This should prevent busy loops where the socket is makred readable
but we are really only looking for it to become writable.

src/network/tls.h

@@ -32,6 +32,8 @@ enum ssl_state
 	tls_st_accepting,
 	tls_st_connecting,
 	tls_st_connected,
+	tls_st_need_read,  /* special case of connected */
+	tls_st_need_write, /* special case of connected */
 	tls_st_disconnecting,
 };