qemu-char: (Re-)connect for tcp_chr_write() unconnected writing

tcp_chr_write() did not deal with writing to an unconnected
connection and return the original length of the data, it's
not right and would cause false writing. So (re-)connect it
and return 0 for this situation.
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NLei Li <lilei@linux.vnet.ibm.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

qemu-char.c

@@ -2141,14 +2141,17 @@ typedef struct {
 
 static void tcp_chr_accept(void *opaque);
 
+static void tcp_chr_connect(void *opaque);
+
 static int tcp_chr_write(CharDriverState *chr, const uint8_t *buf, int len)
 {
     TCPCharDriver *s = chr->opaque;
     if (s->connected) {
         return send_all(s->fd, buf, len);
     } else {
-        /* XXX: indicate an error ? */
-        return len;
+        /* (Re-)connect for unconnected writing */
+        tcp_chr_connect(chr);
+        return 0;
     }
 }