Remove fStencilClearValue from Vulkan's CommandBufferInfo struct

Adding this extra field to the CommandBufferInfo may or may not have led to a memory regression.

Remove it until it is actually needed.

Change-Id: Ibdddbeb7625f91f5199584a575289f07f6e95304
Reviewed-on: https://skia-review.googlesource.com/33280
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
4 files changed