[Libguestfs] [PATCH nbdkit] server: Fix parameters of lock_request, unlock_request

Patch itself is not controversial. However I do wonder if we want to change all these constructs so that instead of using #ifdef we use something like: if (HAVE_PIPE2) { // normal path } else { // fallback } (It wouldn't actually work as written above because HAVE_PIPE2 is not always defined, but you get the idea.) This would allow us to test that the fallback paths still compile. Rich.