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

[Richard W.M. Jones]

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.