[Libguestfs] [PATCH 0/4] common: Add a simple mini-library for handling qemu command and config files.

Currently we have an OCaml library for generating the qemu command line (used only by ‘virt-v2v -o qemu’). However we also generate a qemu command line in ‘lib/launch-direct.c’, and we might in future need to generate a ‘-readconfig’-compatible configuration file if we want to go beyond 10,000 drives for scalability testing. Therefore this patch series reimplements the qemu command line code as a small C library (common/qemuopts), extends it to support qemu config files, and then reimplements both ‘lib/launch-direct.c’ and ‘virt-v2v -o qemu’ to use it. It also fixes a few bugs. In particular we don't properly comma-quote qemu parameters in multiple places. This fixes all of those places properly. It also drops support for ‘./configure --with-qemu-options’ which is broken (see commit message). Rich.