add hyperv enlightments : hv_reset, hv_vpindex, hv_runtime

add hyperv enlightments : hv_reset, hv_vpindex, hv_runtime

add them by default for qemu 2.6
(support is already present in qemu 2.5, but we don't want to break live migration for current running vm)

vpindex && runtime need host kernel 4.4

Theses 3 enlightements are needed by windows to use vmbus
http://searchwindowsserver.techtarget.com/definition/Microsoft-Virtual-Machine-Bus-VMBus

details :

- When Hyper-V "vpindex" is on, guest can use MSR HV_X64_MSR_VP_INDEX
to get virtual processor ID.

- Hyper-V "runtime" enlightement feature allows to use MSR
HV_X64_MSR_VP_RUNTIME to get the time the virtual processor consumes
running guest code, as well as the time the hypervisor spends running
code on behalf of that guest.

- Hyper-V "reset" allows guest to reset VM.

Signed-off-by: Alexandre Derumier <aderumier@odiso.com>