Vulkan: Fix `BasePipeline` value set in `vkCreate*Pipelines`
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

google/gapid,pmuetschard/gapid,google/agi,Qining/gapid,google/gapid,Qining/gapid,pmuetschard/gapid,google/agi,Qining/gapid,google/agi,Qining/gapid,google/agi,Qining/gapid,google/agi,google/gapid,pmuetschard/gapid,Qining/gapid,pmuetschard/gapid,pmuetschard/gapid,google/gapid,pmuetschard/gapid,google/gapid,Qining/gapid,pmuetschard/gapid,google/gapid,pmuetschard/gapid,google/agi,google/gapid,google/agi,Qining/gapid,google/gapid,google/agi