turnip: Fix vkCmdCopyQueryPoolResults with available flag

Previously, calling vkCmdCopyQueryPoolResults with the
VK_QUERY_RESULT_WITH_AVAILABILITY_BIT flag set the query result
field in the buffer to 0 if unavailable and the query result if
available. This was a misunderstanding of the Vulkan spec, and this
commit corrects the behavior to emitting a separate available
result in addition to the query result.

Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3560>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3560>