MINOR: tcp/uxst/sockpair: use fd_want_send() instead of conn_xprt_want_send()

Just like previous commit, we don't need to pass through the connection
layer anymore to enable polling during a connect(), we know the FD, so
let's simply call fd_want_send().
diff --git a/src/proto_sockpair.c b/src/proto_sockpair.c
index bdc7ebe..75cdfd4 100644
--- a/src/proto_sockpair.c
+++ b/src/proto_sockpair.c
@@ -332,7 +332,7 @@
 		return SF_ERR_RESOURCE;
 	}
 
-	conn_xprt_want_send(conn);  /* for connect status, proxy protocol or SSL */
+	fd_want_send(fd);  /* for connect status, proxy protocol or SSL */
 	return SF_ERR_NONE;  /* connection is OK */
 }
 
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 8486863..6f63e3f 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -585,7 +585,7 @@
 		return SF_ERR_RESOURCE;
 	}
 
-	conn_xprt_want_send(conn);  /* for connect status, proxy protocol or SSL */
+	fd_want_send(fd);  /* for connect status, proxy protocol or SSL */
 	return SF_ERR_NONE;  /* connection is OK */
 }
 
diff --git a/src/proto_uxst.c b/src/proto_uxst.c
index 61c89d5..2d5ac71 100644
--- a/src/proto_uxst.c
+++ b/src/proto_uxst.c
@@ -587,7 +587,7 @@
 		return SF_ERR_RESOURCE;
 	}
 
-	conn_xprt_want_send(conn);  /* for connect status, proxy protocol or SSL */
+	fd_want_send(fd);  /* for connect status, proxy protocol or SSL */
 	return SF_ERR_NONE;  /* connection is OK */
 }