diff -urN v2.4.9-ac15/include/linux/compiler.h foo/include/linux/compiler.h
--- v2.4.9-ac15/include/linux/compiler.h	Wed Dec 31 19:00:00 1969
+++ foo/include/linux/compiler.h	Wed Sep 26 17:44:02 2001
@@ -0,0 +1,16 @@
+#ifndef __LINUX_COMPILER_H
+#define __LINUX_COMPILER_H
+
+/* Somewhere in the middle of the GCC 2.96 development cycle, we implemented
+   a mechanism by which the user can annotate likely branch directions and
+   expect the blocks to be reordered appropriately.  Define __builtin_expect
+   to nothing for earlier compilers.  */
+
+#if __GNUC__ == 2 && __GNUC_MINOR__ < 96
+#define __builtin_expect(x, expected_value) (x)
+#endif
+
+#define likely(x)	__builtin_expect((x),1)
+#define unlikely(x)	__builtin_expect((x),0)
+
+#endif /* __LINUX_COMPILER_H */