Add some copy support for vulkan msaa

src/gpu/vk/GrVkRenderTarget.cpp

Index: src/gpu/vk/GrVkRenderTarget.cpp
diff --git a/src/gpu/vk/GrVkRenderTarget.cpp b/src/gpu/vk/GrVkRenderTarget.cpp
index 59fc0b980d353e40861fb3af6221213baf0fb8b8..6d95ba0d00a294daa9bb30a811da0e2982986455 100644
--- a/src/gpu/vk/GrVkRenderTarget.cpp
+++ b/src/gpu/vk/GrVkRenderTarget.cpp
@@ -135,7 +135,9 @@ GrVkRenderTarget::Create(GrVkGpu* gpu,
         msImageDesc.fLevels = 1;
         msImageDesc.fSamples = desc.fSampleCnt;
         msImageDesc.fImageTiling = VK_IMAGE_TILING_OPTIMAL;
-        msImageDesc.fUsageFlags = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
+        msImageDesc.fUsageFlags = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT |
+                                  VK_IMAGE_USAGE_TRANSFER_DST_BIT |
+                                  VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
         msImageDesc.fMemProps = VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT;
 
         if (!GrVkImage::InitImageInfo(gpu, msImageDesc, &msInfo)) {