lguest: barrier me harder
lguest: barrier me harder

Impact: barrier correctness in example launcher

I doubt either lguest user will complain about performance.

Reported-by: Christoph Hellwig <923f7720577207a44b32e59bbfbea59d27f1ae8e@infradead.org>
Cc: Jens Axboe <165ab144a3ccfd9429d5c6466b275f24fafdb114@oracle.com>
Signed-off-by: Rusty Russell <df9728c9e5104131c08c7adb03af425394842596@rustcorp.com.au>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas