[libvirt] [PATCH 00/20] Prepare QEMU capabilities for detection via QMP

As of QEMU 1.2 libvirt is supposed to stop parsing -help and instead use various QMP commands to detect capabilities. Before we can do this, the current QEMU capabilities code needs a serious cleanup and some refactoring. This series does that major preparation work. Currently we consider "capabilities" to just refer to flags we detect from -help. This series expands to cover all the things we detect from QEMU, specifically including machine types, CPU definitions and architecture. It introduces a single object to track all this data and a centralized caching mechanism so we never re-query data we already have somewhere.