MFC r263259
Add Tx/Rx multiqueue support to vmx(4)

As a prerequisite for multiple queues, the guest must have MSIX enabled.
Unfortunately, to work around device passthrough bugs, FreeBSD disables
MSIX when running as a VMWare guest due to the hw.pci.honor_msi_blacklist
tunable; this tunable must be disabled for multiple queues.

Also included is various minor changes from the projects/vmxnet branch.

MFC r264865
Update the date that was missed in r263259

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Include bsd.own.mk before trying to check MK_* values.

Add vmx(4), a VMware VMXNET3 ethernet driver ported from OpenBSD