posixtest: run tests against normal filesystem

Change-Id: I4c61fa0f522fa07d0c02d8c7261a6c82ab6756a8

posixtest/posixtest_test.go

+// Copyright 2023 the Go-FUSE 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 posixtest
+
+import "testing"
+
+func TestAll(t *testing.T) {
+	for k, fn := range All {
+		if k == "FcntlFlockLocksFile" {
+			// TODO - fix this test.
+			continue
+		}
+		t.Run(k, func(t *testing.T) {
+			dir := t.TempDir()
+			fn(t, dir)
+		})
+	}
+}