memblock tests: Add skeleton of the memblock simulator

Add basic project files, together with local stubs of required headers.
Update tools/include/slab.h to include definitions used by memblock.

Signed-off-by: Karolina Drobnik <karolinadrobnik@gmail.com>
Signed-off-by: Mike Rapoport <rppt@kernel.org>
Link: https://lore.kernel.org/r/d296fceb023a04b316a31fbff9acf1e76ac684e4.1643796665.git.karolinadrobnik@gmail.com

tools/testing/memblock/linux/printk.h

@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PRINTK_H
+#define _PRINTK_H
+
+#include <stdio.h>
+#include <asm/bug.h>
+
+/*
+ * memblock_dbg is called with u64 arguments that don't match the "%llu"
+ * specifier in printf. This results in warnings that cannot be fixed without
+ * modifying memblock.c, which we wish to avoid. As these messaged are not used
+ * in testing anyway, the mismatch can be ignored.
+ */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat"
+#define printk printf
+#pragma GCC diagnostic push
+
+#define pr_info printk
+#define pr_debug printk
+#define pr_cont printk
+#define pr_err printk
+#define pr_warn printk
+
+#endif