memblock test: fix implicit declaration of function 'memparse'

Commit 1e4c64b71c9b ("mm/memblock: Add "reserve_mem" to reserved named
memory at boot up") introduce the usage of memparse(), which is not
defined in memblock test.

Add the definition and link it to fix the build.

Signed-off-by: Wei Yang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mike Rapoport (Microsoft) <[e-mail]>

tools/include/linux/string.h

···
 extern char *strim(char *);
 
 extern void *memchr_inv(const void *start, int c, size_t bytes);
+extern unsigned long long memparse(const char *ptr, char **retptr);
 #endif /* _TOOLS_LINUX_STRING_H_ */

tools/lib/cmdline.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * From lib/cmdline.c
+ */
+#include <stdlib.h>
+
+#if __has_attribute(__fallthrough__)
+# define fallthrough                    __attribute__((__fallthrough__))
+#else
+# define fallthrough                    do {} while (0)  /* fallthrough */
+#endif
+
+unsigned long long memparse(const char *ptr, char **retptr)
+{
+	char *endptr;	/* local pointer to end of parsed string */
+
+	unsigned long long ret = strtoll(ptr, &endptr, 0);
+
+	switch (*endptr) {
+	case 'E':
+	case 'e':
+		ret <<= 10;
+		fallthrough;
+	case 'P':
+	case 'p':
+		ret <<= 10;
+		fallthrough;
+	case 'T':
+	case 't':
+		ret <<= 10;
+		fallthrough;
+	case 'G':
+	case 'g':
+		ret <<= 10;
+		fallthrough;
+	case 'M':
+	case 'm':
+		ret <<= 10;
+		fallthrough;
+	case 'K':
+	case 'k':
+		ret <<= 10;
+		endptr++;
+		fallthrough;
+	default:
+		break;
+	}
+
+	if (retptr)
+		*retptr = endptr;
+
+	return ret;
+}

tools/testing/memblock/Makefile

···
 TARGETS = main
 TEST_OFILES = tests/alloc_nid_api.o tests/alloc_helpers_api.o tests/alloc_api.o \
 		  tests/basic_api.o tests/common.o tests/alloc_exact_nid_api.o
-DEP_OFILES = memblock.o lib/slab.o mmzone.o slab.o
+DEP_OFILES = memblock.o lib/slab.o mmzone.o slab.o cmdline.o
 OFILES = main.o $(DEP_OFILES) $(TEST_OFILES)
 EXTR_SRC = ../../../mm/memblock.c
 

tools/testing/memblock/linux/kernel.h

···
 #include <linux/printk.h>
 #include <linux/linkage.h>
 #include <linux/kconfig.h>
+#include <linux/string.h>
 
 #endif