[Libguestfs] [PATCH 0/4] lib: qemu: Add test for mandatory locking.

The patch I posted last week to disable mandatory locking for readonly drives (https://www.redhat.com/archives/libguestfs/2017-September/msg00013.html) was wrong in a couple of respects. Firstly it didn't work, which I didn't detect because my tests were testing the wrong thing. Oops. Secondly it used a simple version number check to detect qemu binaries implementing mandatory locking. This patch series addresses the second issue. It refactors the code which tests qemu features to make it more manageable. Then it implements QMP testing, and finally it adds a slightly braindead (but working) test for whether the qemu binary implements mandatory locking based on features of the binary and not version numbers. I tested this against several qemu binaries with and without locking and it worked for me in all cases. Rich.