ACPICA: Unbreak tools build after switching over to strscpy_pad()

Commit 97f7d3f9c9 ("ACPICA: Replace strncpy() with strscpy_pad() in
acpi_ut_safe_strncpy()") switched over the ACPICA code in the kernel to
using strscpy_pad() instead of a combination of strncpy() and manual
NUL-termination of the destination string, but it overlooked the fact
that tools also use the code in question and strscpy_pad() is not
defined in those builds.

Address that by using the original ACPICA code in non-kernel builds.

Fixes: 97f7d3f9c9 ("ACPICA: Replace strncpy() with strscpy_pad() in acpi_ut_safe_strncpy()")
Reported-by: Jiri Slaby <[email protected]>
Closes: https://lore.kernel.org/all/79e9e913-0fb1-4110-804b-c3b5d0edafe4@kernel
Signed-off-by: Rafael J. Wysocki <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
[ rjw: Fixed up the number of added code lines ]
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Rafael J. Wysocki <[email protected]>

drivers/acpi/acpica/utnonansi.c

@@ -168,7 +168,16 @@ void acpi_ut_safe_strncpy(char *dest, char *source, acpi_size dest_size)
 {
 	/* Always terminate destination string */
 
+#ifdef __KERNEL__
 	strscpy_pad(dest, source, dest_size);
+#else
+	/*
+	 * strscpy_pad() is not defined in ACPICA tools builds, so use strncpy()
+	 * and directly NUL-terminate the destination string in that case.
+	 */
+	strncpy(dest, source, dest_size);
+	dest[dest_size - 1] = 0;
+#endif
 }
 
 #endif