The LXC driver was mistakenly returning -1 for lxcStartup()
in scenarios that are not an error. This caused the libvirtd
to quit for unprivileged users. This fixes the return code
of LXC driver, and also adds a "name" field to the virStateDriver
struct and logging to make it easier to find these problems
in the future

* src/driver.h: Add a 'name' field to state driver to allow
  easy identification during failures
* src/libvirt.c: Log name of failed driver for virStateInit
  failures
* src/lxc/lxc_driver.c: Don't return a failure code for
  lxcStartup() if LXC is not available on this host, simply
  disable the driver.
* src/network/bridge_driver.c, src/node_device/node_device_devkit.c,
  src/node_device/node_device_hal.c, src/opennebula/one_driver.c,
  src/qemu/qemu_driver.c, src/remote/remote_driver.c,
  src/secret/secret_driver.c, src/storage/storage_driver.c,
  src/uml/uml_driver.c, src/xen/xen_driver.c: Fill in name
  field in virStateDriver struct