[acpica] Avoid undefined behavior

Upstream: https://github.com/acpica/acpica/pull/846

Bug: 41663
Change-Id: I9badf527f667301d1fb3b09e38e5bb4bc7ce46eb
diff --git a/source/include/platform/aclinux.h b/source/include/platform/aclinux.h
index 2c70db1..69ebb38 100644
--- a/source/include/platform/aclinux.h
+++ b/source/include/platform/aclinux.h
@@ -202,7 +202,10 @@
 #define ACPI_USE_STANDARD_HEADERS
 
 #ifdef ACPI_USE_STANDARD_HEADERS
+#include <stddef.h>
 #include <unistd.h>
+
+#define ACPI_OFFSET(d, f)           offsetof(d, f)
 #endif
 
 /* Define/disable kernel-specific declarators */