vfio-ioctls v0.4.0

Added

• Enable support for Microsoft Hyper-V.
• VfioError now propagates the underlying error for more error
  types.
• Many structs now derive Eq where it makes sense.
• Added VfioDevice::set_irq_resample_fd to unmask level-triggered
  IRQs via an eventfd.

Changed

• We skipped to version 0.4.0 to harmonize versions with
  vfio-bindings.
• The device handle in VfioContainer::new has become optional.
• Device file descriptors have their own type (VfioDeviceFd) to hide
  the underlying hypervisor-specific types.
• Fixed file descriptor handling on big endian architectures.
• Avoid logging errors for querying VGA regions for devices that don't
  have them.