MINOR: connection: don't check for CO_FL_SOCK_WR_SH too early in handshakes

Just like with CO_FL_SOCK_RD_SH, we don't need to check for this flag too
early because conn_sock_send() already does it. No error was lost so it
was harmless, it was only useless code.
diff --git a/src/connection.c b/src/connection.c
index 83790a9..ced919f 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -1003,10 +1003,6 @@
 {
 	struct socks4_request req_line;
 
-	/* we might have been called just after an asynchronous shutw */
-	if (conn->flags & CO_FL_SOCK_WR_SH)
-		goto out_error;
-
 	if (!conn_ctrl_ready(conn))
 		goto out_error;
 
diff --git a/src/stream_interface.c b/src/stream_interface.c
index 0a2e7d1..14e6627 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -329,10 +329,6 @@
  */
 int conn_si_send_proxy(struct connection *conn, unsigned int flag)
 {
-	/* we might have been called just after an asynchronous shutw */
-	if (conn->flags & CO_FL_SOCK_WR_SH)
-		goto out_error;
-
 	if (!conn_ctrl_ready(conn))
 		goto out_error;