anv: Handle unavailable queries in vkCmdCopyQueryPoolResults

anv: Handle unavailable queries in vkCmdCopyQueryPoolResults

If VK_QUERY_RESULT_WAIT_BIT is not set, there is currently no
special handling of unavailable queries in vkCmdCopyQueryPoolResults,
and anv will write an invalid value for the query result.

This commit updates vkCmdCopyQueryPoolResults for unavailable
queries to return 0 if the VK_QUERY_RESULT_PARTIAL_BIT flag is set
and if not, skip writing altogether.

Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3586>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3586>