chardev: close an fd on failure path

There are at least two failure paths, where we forget
to close an fd.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

chardev/char-pty.c

@@ -350,6 +350,7 @@ static void char_pty_open(Chardev *chr,
 
     close(slave_fd);
     if (!qemu_set_blocking(master_fd, false, errp)) {
+        close(master_fd);
         return;
     }
 

chardev/char-serial.c

@@ -272,6 +272,7 @@ static void qmp_chardev_open_serial(Chardev *chr,
         return;
     }
     if (!qemu_set_blocking(fd, false, errp)) {
+        close(fd);
         return;
     }
     tty_serial_init(fd, 115200, 'N', 8, 1);