Mainly for completeness, but it has practical uses: someone retrieving
a QRhi instance from somewhere should be able to tell the
QVulkanInstance, and so the VkInstance, used by that QRhi without
resorting to investigating other objects (e.g. retrieving the instance
from the QWindow). This provides symmetry to other 3D APIs and QRhi
backends where just a single QRhi instance is sufficient to get the
MTLDevice, ID3D11Device/Context, etc. i.e. all that is needed to
work with the 3D API directly.
Change-Id: I5a8b9871a543ea648c76b868bf6ff7be5f2098f2
Reviewed-by: Jonas Karlsson <jonas.karlsson@qt.io>
Reviewed-by: Hatem ElKharashy <hatem.elkharashy@qt.io>
afe0bf0914