Vulkan fixes for TesselatingPathRenderer test

src/gpu/vk/GrVkBuffer.h

Index: src/gpu/vk/GrVkBuffer.h
diff --git a/src/gpu/vk/GrVkBuffer.h b/src/gpu/vk/GrVkBuffer.h
index bb053ccce0df332dbdce0ef4e551742ebb077ea7..3ea9b869295906fec43a2e15c5c6fa6e01d71af6 100644
--- a/src/gpu/vk/GrVkBuffer.h
+++ b/src/gpu/vk/GrVkBuffer.h
@@ -81,7 +81,7 @@ protected:
     }
 
     void* vkMap(const GrVkGpu* gpu);
-    void vkUnmap(const GrVkGpu* gpu);
+    void vkUnmap(GrVkGpu* gpu);
     // If the caller passes in a non null createdNewBuffer, this function will set the bool to true
     // if it creates a new VkBuffer to upload the data to.
     bool vkUpdateData(GrVkGpu* gpu, const void* src, size_t srcSizeInBytes,