d3d12: Implement D3D12SerializeRootSignature().

dlls/d3d12/d3d12.spec

@@ -5,4 +5,4 @@
 104 stub D3D12CoreGetLayeredDeviceSize
 105 stub D3D12CoreRegisterLayers
 106 stdcall D3D12CreateRootSignatureDeserializer(ptr long ptr ptr)
-107 stub D3D12SerializeRootSignature
+107 stdcall D3D12SerializeRootSignature(ptr long ptr ptr)

dlls/d3d12/d3d12_main.c

@@ -58,3 +58,12 @@ HRESULT WINAPI D3D12CreateRootSignatureDeserializer(const void *data, SIZE_T dat
 
     return vkd3d_create_root_signature_deserializer(data, data_size, iid, deserializer);
 }
+
+HRESULT WINAPI D3D12SerializeRootSignature(const D3D12_ROOT_SIGNATURE_DESC *root_signature_desc,
+        D3D_ROOT_SIGNATURE_VERSION version, ID3DBlob **blob, ID3DBlob **error_blob)
+{
+    TRACE("root_signature_desc %p, version %#x, blob %p, error_blob %p.\n",
+            root_signature_desc, version, blob, error_blob);
+
+    return vkd3d_serialize_root_signature(root_signature_desc, version, blob, error_blob);
+}