Implement various vulkan stencil clears and fix various stenciling bugs.

src/gpu/vk/GrVkRenderPass.cpp

Index: src/gpu/vk/GrVkRenderPass.cpp
diff --git a/src/gpu/vk/GrVkRenderPass.cpp b/src/gpu/vk/GrVkRenderPass.cpp
index 9c4787b865cb3bce8ef6e271e37bfd5d9931357d..958d604f546c658a502ee4670a2a4f22f8d37512 100644
--- a/src/gpu/vk/GrVkRenderPass.cpp
+++ b/src/gpu/vk/GrVkRenderPass.cpp
@@ -22,7 +22,7 @@ void setup_simple_vk_attachment_description(VkAttachmentDescription* attachment,
     attachment->loadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
     attachment->storeOp = VK_ATTACHMENT_STORE_OP_STORE;
     attachment->stencilLoadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
-    attachment->storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+    attachment->stencilStoreOp = VK_ATTACHMENT_STORE_OP_STORE;
     attachment->initialLayout = layout;
     attachment->finalLayout = layout;
 }