PassHazards keeps the guest ranges, images and attachments the draws
since the last barrier read and wrote, and answers whether a new draw has
a RAW, WAW or WAR hazard against them. Address-based reads and unknown
writes count as touching any guest memory; attachments of the current
pass are ordered by rasterization and only conflict with other passes or
with sampled and storage uses. Unit tests in agc_pass_hazards.
Dean Galvin