Implement various vulkan stencil clears and fix various stenciling bugs.

src/gpu/vk/GrVkCommandBuffer.cpp

Index: src/gpu/vk/GrVkCommandBuffer.cpp
diff --git a/src/gpu/vk/GrVkCommandBuffer.cpp b/src/gpu/vk/GrVkCommandBuffer.cpp
index e43c50fc4ac44bdeaeb546002cc86fd6a614f920..af264534d7a199312fd3bc43e151687e09ea5a62 100644
--- a/src/gpu/vk/GrVkCommandBuffer.cpp
+++ b/src/gpu/vk/GrVkCommandBuffer.cpp
@@ -104,7 +104,6 @@ void GrVkCommandBuffer::beginRenderPass(const GrVkGpu* gpu,
     fActiveRenderPass = renderPass;
     this->addResource(renderPass);
     target.addResources(*this);
-
 }
 
 void GrVkCommandBuffer::endRenderPass(const GrVkGpu* gpu) {
@@ -295,6 +294,22 @@ void GrVkCommandBuffer::clearColorImage(const GrVkGpu* gpu,
                                                       subRanges));
 }
 
+void GrVkCommandBuffer::clearStencilImage(const GrVkGpu* gpu,

[jvanverth1, 2016/03/01 18:49:10]

We will probably add a depth buffer at some point, so it might be more accurate
to call this clearDepthStencilImage (since it could be used for either/both).

[egdaniel, 2016/03/01 20:34:38]

Done.

+                                          GrVkImage* image,
+                                          const VkClearDepthStencilValue* color,
+                                          uint32_t subRangeCount,
+                                          const VkImageSubresourceRange* subRanges) {
+    SkASSERT(fIsActive);
+    SkASSERT(!fActiveRenderPass);
+    this->addResource(image->resource());
+    GR_VK_CALL(gpu->vkInterface(), CmdClearDepthStencilImage(fCmdBuffer,
+                                                             image->textureImage(),
+                                                             image->currentLayout(),
+                                                             color,
+                                                             subRangeCount,
+                                                             subRanges));
+}
+
 void GrVkCommandBuffer::clearAttachments(const GrVkGpu* gpu,
                                          int numAttachments,
                                          const VkClearAttachment* attachments,