It is illegal to match a SPIR-V multisampled resource to a Vulkan resource which
is not multisampled. Vulkan considers a resource to be multisampled if its
sample count is greater than 1 (and SPIR-V does not care about the sample count).
This fixes validation errors in the case where the sample count does actually
match the resource. In order to provide correct behaviour when there is a
mismatch, or when the sample count is missing, we will need yet another
additional interface. In the absence of that it seems best to provide a best
guess.
This fixes a validation error with the not-yet-committed merge request 135, when
the d3d11 runner is run through Wine with the Vulkan backend.
From this point on, it is no longer true that only hlsl_ir_loads can
return objects, because an object can also come from chain of
hlsl_ir_indexes that ends in an hlsl_ir_load.
The lower_index_loads pass takes care of lowering all hlsl_ir_indexes
into hlsl_ir_loads.
For this reason, hlsl_resource_load_params now expects both the resource
as the sampler to be just an hlsl_ir_node pointer instead of a pointer
to a more specific hlsl_ir_load.
This node type is intended for use during parse-time.
While we parse an indexing expression such as "a[3]", we don't know if
it will end up as part of an expression (in which case it must be folded
into a load) or it is for the lhs of a store (in which case it must be
folded into the store's deref).
