Fix Coverty CID #96210: Argument cannot be negative.

We must check the return value from `accept()`, it may fail.  Also, we
should probably retry the syscall in some cases ...

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

api.c

@@ -126,9 +126,15 @@ static int do_query_inetd(char *buf, size_t len)
 
 static void cb(uev_t *w, void *UNUSED(arg), int UNUSED(events))
 {
-	int sd = accept(w->fd, NULL, NULL);
+	int sd;
 	struct init_request rq;
 
+	sd = accept(w->fd, NULL, NULL);
+	if (sd < 0) {
+		_pe("Failed serving API request");
+		return;
+	}
+
 	while (1) {
 		int result = 0;
 		ssize_t len;