Improved pNext pointer handling

- Added a loop for handling pNext pointers everywhere in
  libVulkan.cpp where the wasn't already one, in order to
  always output the unsupported structure type(s) received
  by the library
- Changed UNIMPLEMENTED to WARN for unhandled pNext pointers

Fixes the test:
dEQP-VK.api.smoke.triangle_ext_structs

Bug: b/144999059 b/119321052
Change-Id: Id83b5e74c8925dbd38651747b0cea46fac4a69a4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/38548
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Sean Risser <srisser@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>

src/Vulkan/VkPipeline.cpp

diff --git a/src/Vulkan/VkPipeline.cpp b/src/Vulkan/VkPipeline.cpp
index cbb79c7..9a4f34f 100644
--- a/src/Vulkan/VkPipeline.cpp
+++ b/src/Vulkan/VkPipeline.cpp
@@ -18,6 +18,7 @@
 #include "VkPipelineCache.hpp"
 #include "VkPipelineLayout.hpp"
 #include "VkShaderModule.hpp"
+#include "VkStringify.hpp"
 #include "VkRenderPass.hpp"
 #include "Pipeline/ComputeProgram.hpp"
 #include "Pipeline/SpirvShader.hpp"
@@ -419,7 +420,7 @@
 		}
 		break;
 		default:
-			UNIMPLEMENTED("extensionCreateInfo->sType");
+			WARN("pCreateInfo->pRasterizationState->pNext sType = %s", vk::Stringify(extensionCreateInfo->sType));
 			break;
 		}