Fix color blend state in multisample tests

If the subpass the pipeline is created with has no color attachment the
attachmentCount of pColorBlendState must also be 0

Components: Vulkan

VK-GL-CTS issue: 3991

Affected tests:
dEQP-VK.pipeline.multisample.alpha_to_coverage_no_color_attachment.*

Change-Id: I37ca31e3114ca3e840759b118365f41b1a9565a1
diff --git a/external/vulkancts/modules/vulkan/pipeline/vktPipelineMultisampleTests.cpp b/external/vulkancts/modules/vulkan/pipeline/vktPipelineMultisampleTests.cpp
index 6615ada..cf3f21c 100644
--- a/external/vulkancts/modules/vulkan/pipeline/vktPipelineMultisampleTests.cpp
+++ b/external/vulkancts/modules/vulkan/pipeline/vktPipelineMultisampleTests.cpp
@@ -3163,7 +3163,7 @@
 		for (deUint32 attachmentIdx = 0; attachmentIdx < attachmentCount; attachmentIdx++)
 			attachments.push_back(m_colorBlendState);
 
-		const VkPipelineColorBlendStateCreateInfo colorBlendStateParams =
+		VkPipelineColorBlendStateCreateInfo colorBlendStateParams =
 		{
 			VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO,	// VkStructureType								sType;
 			DE_NULL,													// const void*									pNext;
@@ -3205,6 +3205,18 @@
 		const deUint32 numSubpasses = m_renderType == RENDER_TYPE_DEPTHSTENCIL_ONLY ? 2u : 1u;
 
 		for (deUint32 subpassIdx = 0; subpassIdx < numSubpasses; subpassIdx++)
+		{
+			if (m_renderType == RENDER_TYPE_DEPTHSTENCIL_ONLY)
+			{
+				if (subpassIdx == 0)
+				{
+					colorBlendStateParams.attachmentCount = 0;
+				}
+				else
+				{
+					colorBlendStateParams.attachmentCount = 1;
+				}
+			}
 			for (deUint32 i = 0u; i < numTopologies; ++i)
 			{
 				m_graphicsPipelines.push_back(VkPipelineSp(new Unique<VkPipeline>(makeGraphicsPipeline(vk,							// const DeviceInterface&                        vk
@@ -3227,6 +3239,7 @@
 																									   &depthStencilStateParams,	// const VkPipelineDepthStencilStateCreateInfo*  depthStencilStateCreateInfo
 																									   &colorBlendStateParams))));	// const VkPipelineColorBlendStateCreateInfo*    colorBlendStateCreateInfo
 			}
+			}
 	}
 
 	if (m_renderType == RENDER_TYPE_COPY_SAMPLES)