Remove asserts blocking pipeline derivatives

* Implementations must ignore basePipelineIndex & basePipelineHandle
  if VK_PIPELINE_CREATE_DERIVATIVE_BIT is not specified.
* We choose to ignore the pipeline derivative controls entirely.
  This is consistent with other implementations.
* Also remove assert blocking pipeline construction for subpasses
  other than 0. This works fine.

Test: dEQP-VK.pipeline.derivative.compute.*
Change-Id: Ia03508b33397c60a3de5caf8536f7d75058738f6
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/27828
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Tested-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>

src/Vulkan/VkPipeline.cpp

@@ -254,13 +254,10 @@ Pipeline::Pipeline(PipelineLayout const *layout) : layout(layout) {}
 GraphicsPipeline::GraphicsPipeline(const VkGraphicsPipelineCreateInfo* pCreateInfo, void* mem)
 	: Pipeline(Cast(pCreateInfo->layout))
 {
-	if((pCreateInfo->flags != 0) ||
+	if(((pCreateInfo->flags & ~(VK_PIPELINE_CREATE_DERIVATIVE_BIT | VK_PIPELINE_CREATE_ALLOW_DERIVATIVES_BIT)) != 0) ||
 	   (pCreateInfo->stageCount != 2) ||
 	   (pCreateInfo->pTessellationState != nullptr) ||
-	   (pCreateInfo->pDynamicState != nullptr) ||
-	   (pCreateInfo->subpass != 0) ||
-	   (pCreateInfo->basePipelineHandle != VK_NULL_HANDLE) ||
-	   (pCreateInfo->basePipelineIndex != 0))
+	   (pCreateInfo->pDynamicState != nullptr))
 	{
 		UNIMPLEMENTED("pCreateInfo settings");
 	}