Inhibit daemon shutdown during driver initialization

Inhibit daemon shutdown during driver initialization

As of 1a50ba2cb07d8bb2aa724062889deb9efd7ad9e9 qemu capabilities probing
takes longer since we timeout waiting for the monitor socket. When
probing qemu for different architectures this can add up so the daemon
auto shutdown timeout is reached and the client doesn't have a chance
to connect. To avoid that inhibit daemon shutdown during driver
initialization (which includes capabilities probing).

This fixes

	http://honk.sigxcpu.org:8001/job/libvirt-tck-debian-wheezy-qemu-session/227/