Implement a HCI passthrough to host.

This allows using a host's physical HCI as one of the HCIs attached
to the virtual machine.  This brings various limitations because not
all commands/events are passed through by Linux kernel, some are
interpreted by the host's kernel for a speed gain.


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5344 c046a42c-6fe2-441c-8c8c-71466251a162
