MFC 322488
hyperv: Update copyright for the files changed in 2017

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D11982

MFC 311743

hyperv: Add method to read 64bit Hyper-V specific time value.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D9057

MFC 310462,310465

310462
hyperv/ic: Fix version4 timesync message format.

It is not compat w/ the old timesync message format, which the message
type stays the same as the old timesync message.

Sponsored by: Microsoft

310465
hyperv/ic: Allow applying the samples from hypervisor unconditionally.

Sponsored by: Microsoft

MFC 310324

hyperv/ic: Rename cleaned up files.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8850