MINOR: dynbuf: use regular lists instead of mt_lists for buffer_wait

There's no point anymore in keeping mt_lists for the buffer_wait and
buffer_wq since it's thread-local now.

(cherry picked from commit 90f366b59556f9e64c927286bfc8e9c06d511744)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/mux_fcgi.c b/src/mux_fcgi.c
index 7c88e1a..855cb5a 100644
--- a/src/mux_fcgi.c
+++ b/src/mux_fcgi.c
@@ -602,11 +602,11 @@
 {
 	struct buffer *buf = NULL;
 
-	if (likely(!MT_LIST_ADDED(&fconn->buf_wait.list)) &&
+	if (likely(!LIST_ADDED(&fconn->buf_wait.list)) &&
 	    unlikely((buf = b_alloc_margin(bptr, 0)) == NULL)) {
 		fconn->buf_wait.target = fconn;
 		fconn->buf_wait.wakeup_cb = fcgi_buf_available;
-		MT_LIST_ADDQ(&ti->buffer_wq, &fconn->buf_wait.list);
+		LIST_ADDQ(&ti->buffer_wq, &fconn->buf_wait.list);
 	}
 	return buf;
 }
@@ -758,7 +758,7 @@
 	br_init(fconn->mbuf, sizeof(fconn->mbuf) / sizeof(fconn->mbuf[0]));
 	fconn->streams_by_id = EB_ROOT;
 	LIST_INIT(&fconn->send_list);
-	MT_LIST_INIT(&fconn->buf_wait.list);
+	LIST_INIT(&fconn->buf_wait.list);
 
 	conn->ctx = fconn;
 
@@ -837,8 +837,8 @@
 
 		TRACE_DEVEL("freeing fconn", FCGI_EV_FCONN_END, conn);
 
-		if (MT_LIST_ADDED(&fconn->buf_wait.list))
-			MT_LIST_DEL(&fconn->buf_wait.list);
+		if (LIST_ADDED(&fconn->buf_wait.list))
+			LIST_DEL_INIT(&fconn->buf_wait.list);
 
 		fcgi_release_buf(fconn, &fconn->dbuf);
 		fcgi_release_mbuf(fconn);