tools: bootconfig: Add bootconfig command

Add "bootconfig" command which operates the bootconfig
config-data on initrd image.

User can add/delete/verify the boot config on initrd
image using this command.

e.g.
Add a boot config to initrd image
 # bootconfig -a myboot.conf /boot/initrd.img

Remove it.
 # bootconfig -d /boot/initrd.img

Or verify (and show) it.
 # bootconfig /boot/initrd.img

Link: http://lkml.kernel.org/r/157867223582.17873.14342161849213219982.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
[ Removed extra blank line at end of bootconfig.c ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/bootconfig/include/linux/bug.h

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _SKC_LINUX_BUG_H
+#define _SKC_LINUX_BUG_H
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define WARN_ON(cond)	\
+	((cond) ? printf("Internal warning(%s:%d, %s): %s\n",	\
+			__FILE__, __LINE__, __func__, #cond) : 0)
+
+#endif