sandbox: Add architecture header files

This adds required header files for the sandbox architecture, and a basic
description of what sandbox is (README.sandbox).

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/include/asm/system.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef __ASM_SANDBOX_SYSTEM_H
+#define __ASM_SANDBOX_SYSTEM_H
+
+/* Define this as nops for sandbox architecture */
+static inline void local_irq_save(unsigned flags __attribute__((unused)))
+{
+}
+
+#define local_irq_enable()
+#define local_irq_disable()
+#define local_save_flags(x)
+#define local_irq_restore(x)
+
+#endif