compiler/testdata: add structs.HostLayout

Author: ydnar

compiler/testdata/errors.go

@@ -1,6 +1,9 @@
 package main
 
-import "unsafe"
+import (
+	"structs"
+	"unsafe"
+)
 
 //go:wasmimport modulename empty
 func empty()
@@ -14,6 +17,7 @@ func implementation() {
 type Uint uint32
 
 type S struct {
+	_ structs.HostLayout
 	a [4]uint32
 	b uintptr
 	d float32