tools/testing: abstract two init.h into common include directory

Currently we have two test suits define its own init.h. This is a little
redundant.

Let's create a init.h in common include directory and merge these two
into it.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
CC: Mike Rapoport <rppt@kernel.org>
CC: Liam R. Howlett <Liam.Howlett@oracle.com>
Link: https://lore.kernel.org/r/20240712035138.24674-3-richard.weiyang@gmail.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

tools/include/linux/compiler.h

@@ -126,10 +126,6 @@
 # define unlikely(x)		__builtin_expect(!!(x), 0)
 #endif
 
-#ifndef __init
-# define __init
-#endif
-
 #include <linux/types.h>
 
 /*

tools/include/linux/init.h

@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TOOLS_LINUX_INIT_H_
+#define _TOOLS_LINUX_INIT_H_
+
+#include <linux/compiler.h>
+
+#ifndef __init
+# define __init
+#endif
+
+#ifndef __exit
+# define __exit
+#endif
+
+#define __section(section)              __attribute__((__section__(section)))
+
+#define __initconst
+#define __meminit
+#define __meminitdata
+#define __refdata
+#define __initdata
+
+struct obs_kernel_param {
+	const char *str;
+	int (*setup_func)(char *st);
+	int early;
+};
+
+#define __setup_param(str, unique_id, fn, early)			\
+	static const char __setup_str_##unique_id[] __initconst		\
+		__aligned(1) = str;					\
+	static struct obs_kernel_param __setup_##unique_id		\
+		__used __section(".init.setup")				\
+		__aligned(__alignof__(struct obs_kernel_param)) =	\
+		{ __setup_str_##unique_id, fn, early }
+
+#define early_param(str, fn)						\
+	__setup_param(str, fn, fn, 1)
+
+#endif /*  _TOOLS_LINUX_INIT_H_ */