src/os/stat.go: get build tags right, maybe

Should fix https://github.com/tinygo-org/tinygo/issues/2354

Untested with wasi

src/os/stat.go

@@ -1,5 +1,3 @@
-// +build !baremetal,!js
-
 // Copyright 2017 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

src/os/stat_other.go

@@ -0,0 +1,22 @@
+//  +build baremetal wasm,!wasi
+
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package os
+
+// Sync is a stub, not yet implemented
+func (f *File) Sync() error {
+	return ErrNotImplemented
+}
+
+// statNolog stats a file with no test logging.
+func statNolog(name string) (FileInfo, error) {
+	return nil, &PathError{Op: "stat", Path: name, Err: ErrNotImplemented}
+}
+
+// lstatNolog lstats a file with no test logging.
+func lstatNolog(name string) (FileInfo, error) {
+	return nil, &PathError{Op: "lstat", Path: name, Err: ErrNotImplemented}
+}