[Libvirt-cim] [PATCH 0 of 5] Build and configure cleanups

This patch set started out as just a change to check for a new-enough version of libvirt on the installed system. It evolved into cleaning up a bunch of the package checks in aclocal.m4, a couple of configure cleanups, and a bunch of changes #include statements to account for changes in how we include package directories (which is correct, as of this set, IMHO). Comments and testing on a variety of platforms would be appreciated.