Vulkan: Fix BasePipeline value set in vkCreate*Pipelines

When the `vk*PipelineCreateInfo` specifies a base pipeline by
`basePipelineHandle`, the `basePipelineIndex` is set to -1; the previous code
lost this -1 value, and later in `vk*PipelineCreateInfo`, `BasePipelineIndex`
was 0, causing `BasePipeline` to be set by index, instead of by handle.

This change ensures that `basePipelineIndex` is copied over to the
`*PipelineObject`, so that `BasePipeline` is set correctly.

Fixes #2392

gapis/api/vulkan/api/pipeline.api

@@ -528,11 +528,8 @@ cmd VkResult vkCreateGraphicsPipelines(
     obj.RenderPass = RenderPasses[create_info.renderPass]
     obj.Subpass = create_info.subpass
     if ((as!u32(create_info.flags) & as!u32(VK_PIPELINE_CREATE_DERIVATIVE_BIT)) != 0) {
-      if (create_info.basePipelineIndex != -1) {
-        obj.BasePipelineIndex = create_info.basePipelineIndex
-      } else {
-        obj.BasePipeline = create_info.basePipelineHandle
-      }
+      obj.BasePipelineIndex = create_info.basePipelineIndex
+      obj.BasePipeline = create_info.basePipelineHandle
     } else {
       obj.BasePipelineIndex = 0
       obj.BasePipeline = as!VkPipeline(0)
@@ -625,11 +622,8 @@ cmd VkResult vkCreateComputePipelines(
     }
     obj.Stage = stage_data
     if ((as!u32(info.flags) & as!u32(VK_PIPELINE_CREATE_DERIVATIVE_BIT)) != 0) {
-      if (info.basePipelineIndex != -1) {
-        obj.BasePipelineIndex = info.basePipelineIndex
-      } else {
-        obj.BasePipeline = info.basePipelineHandle
-      }
+      obj.BasePipelineIndex = info.basePipelineIndex
+      obj.BasePipeline = info.basePipelineHandle
     } else {
       obj.BasePipelineIndex = 0
       obj.BasePipeline = as!VkPipeline(0)