Emulate exportable VkDeviceMemory for QnxScreenBuffer memory with server-side allocation

[aruby-blackberry]

... + import during ColorBuffer creation.
    
  ... And add platform_helper_qnx implementation; implements some helpers
  in the gfxstream::qnx namespace, etc..
  
  This change allows QNX to defer the allocation to the gfxtream backend,
  and makes the externalMemory management more uniform across platforms,
  in terms of the way it is managed by the ColorBufferVk object lifetime.

Note: There will be a subsequent change to remove ALL "creation with handle import" code. This effectively negates the requirement for that functionality, as QNX was previously doing the the "server" (QNX Screen) side allocation in the virtio-gpu frontend, and then creating the resource by importing the external handle. However, that was just leaving the vdev to guess when to create a resource this way. This should basically all be internal details of the backend renderer. This makes the frontend implementation AND the backend implementation much easier to understand, and keeps things most similar to other platforms (even ones that are doing typical export-from-Vulkan after allocation).

[aruby-blackberry]

@jmacnak any ideas on the failing end2end test compilation (missing drm_fourcc.h dependency)?

[jmacnak]

@jmacnak any ideas on the failing end2end test compilation (missing drm_fourcc.h dependency)?

It does look like a valid finding. I do not understand why it is only triggered in this PR though since it seems to be a pre-existing issue and this PR does not touch that file... If you can, just add a "@drm//:libdrm", line to

gfxstream/tests/end2end/BUILD.bazel

Line 77 in 3b4da72

deps = [

.

[aruby-blackberry]

@jmacnak thank you1 That fixed it. Looking for reviews now 🙂

[aruby-blackberry]

@jmacnak will this merge automatically? I don't quite know what the kokoro part of the merge checks is ...

[jmacnak]

Internal CI thingy. I think a googler has to trigger it so just spam "@jmacnak" whenever you need it.

[aruby-blackberry]

Internal CI thingy. I think a googler has to trigger it so just spam "@jmacnak" whenever you need it.

Is this fine?

[jmacnak]

It removes the label once it starts running. The "checks" section on this PR shows

with the CI still running. I belive it should automerge once it finishes.