Update min Vulkan version to 1.0.8.0, and fix various bugs

include/gpu/vk/GrVkTypes.h

Index: include/gpu/vk/GrVkTypes.h
diff --git a/include/gpu/vk/GrVkTypes.h b/include/gpu/vk/GrVkTypes.h
index 833f6d30df33123e65d168b51775ab03101f09f9..ac33bf8dad3400a7c7bc845e3692c3fce846c7af 100755
--- a/include/gpu/vk/GrVkTypes.h
+++ b/include/gpu/vk/GrVkTypes.h
@@ -35,6 +35,7 @@ struct GrVkTextureInfo {
     VkDeviceMemory fAlloc;    // this may be null iff the texture is an RT and uses borrow semantics
     VkImageTiling  fImageTiling;
     VkImageLayout  fImageLayout;
+    VkFormat       fFormat;
 };
 
 GR_STATIC_ASSERT(sizeof(GrBackendObject) >= sizeof(const GrVkTextureInfo*));