MEDIUM: connection: complete the polling cleanups

I/O handlers now all use __conn_{sock,data}_{stop,poll,want}_* instead
of returning dummy flags. The code has become slightly simpler because
some tricks such as the MIN_RET_FOR_READ_LOOP are not needed anymore,
and the data handlers which switch to a handshake handler do not need
to disable themselves anymore.
diff --git a/src/raw_sock.c b/src/raw_sock.c
index 80c8fb3..ea2fa66 100644
--- a/src/raw_sock.c
+++ b/src/raw_sock.c
@@ -118,7 +118,7 @@
 				 * which will be able to deal with the situation.
 				 */
 				if (splice_detects_close)
-					conn->flags |= CO_FL_WAIT_DATA; /* we know for sure that it's EAGAIN */
+					__conn_data_poll_recv(conn); /* we know for sure that it's EAGAIN */
 				break;
 			}
 			else if (errno == ENOSYS || errno == EINVAL) {
@@ -168,7 +168,7 @@
 
 		if (ret <= 0) {
 			if (ret == 0 || errno == EAGAIN) {
-				conn->flags |= CO_FL_WAIT_ROOM;
+				__conn_data_poll_send(conn);
 				break;
 			}
 			else if (errno == EINTR)
@@ -245,7 +245,7 @@
 			goto read0;
 		}
 		else if (errno == EAGAIN) {
-			conn->flags |= CO_FL_WAIT_DATA;
+			__conn_data_poll_recv(conn);
 			break;
 		}
 		else if (errno != EINTR) {
@@ -306,7 +306,7 @@
 		}
 		else if (ret == 0 || errno == EAGAIN) {
 			/* nothing written, we need to poll for write first */
-			conn->flags |= CO_FL_WAIT_ROOM;
+			__conn_data_poll_send(conn);
 			break;
 		}
 		else if (errno != EINTR) {