include: add back include/linux for old distributions

However, we don't ship sys/queue.h and netinet/if_ether.h. At some
point, we may want to explore just shipping uapi directory. This has
been tested with Debian 8.

debian/copyright

@@ -58,6 +58,22 @@ License: permissive
  and this notice are preserved. This file is offered as-is, without any
  warranty.
 
+Files: include/linux/*
+Copyright: Copyright (C) 1991-2012 Linus Torvalds
+           and many others
+License: GPL-2+
+ This program is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License
+ as published by the Free Software Foundation; either version
+ 2 of the License, or (at your option) any later version.
+ .
+ On Debian systems, the full text of the GNU General Public
+ License version 2 can be found in the file
+ `/usr/share/common-licenses/GPL-2'.
+Comment:
+ It is believed that header files are an interface for user space and
+ therefore cannot be covered by copyright.
+
 Files: include/osx/*
 Copyright: Copyright (c) 2003-2010 Apple Computer, Inc
 License: APSL-2

include/linux/bpf_common.h

@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef __LINUX_BPF_COMMON_H__
+#define __LINUX_BPF_COMMON_H__
+
+/* Instruction classes */
+#define BPF_CLASS(code) ((code) & 0x07)
+#define		BPF_LD		0x00
+#define		BPF_LDX		0x01
+#define		BPF_ST		0x02
+#define		BPF_STX		0x03
+#define		BPF_ALU		0x04
+#define		BPF_JMP		0x05
+#define		BPF_RET		0x06
+#define		BPF_MISC        0x07
+
+/* ld/ldx fields */
+#define BPF_SIZE(code)  ((code) & 0x18)
+#define		BPF_W		0x00 /* 32-bit */
+#define		BPF_H		0x08 /* 16-bit */
+#define		BPF_B		0x10 /*  8-bit */
+/* eBPF		BPF_DW		0x18    64-bit */
+#define BPF_MODE(code)  ((code) & 0xe0)
+#define		BPF_IMM		0x00
+#define		BPF_ABS		0x20
+#define		BPF_IND		0x40
+#define		BPF_MEM		0x60
+#define		BPF_LEN		0x80
+#define		BPF_MSH		0xa0
+
+/* alu/jmp fields */
+#define BPF_OP(code)    ((code) & 0xf0)
+#define		BPF_ADD		0x00
+#define		BPF_SUB		0x10
+#define		BPF_MUL		0x20
+#define		BPF_DIV		0x30
+#define		BPF_OR		0x40
+#define		BPF_AND		0x50
+#define		BPF_LSH		0x60
+#define		BPF_RSH		0x70
+#define		BPF_NEG		0x80
+#define		BPF_MOD		0x90
+#define		BPF_XOR		0xa0
+
+#define		BPF_JA		0x00
+#define		BPF_JEQ		0x10
+#define		BPF_JGT		0x20
+#define		BPF_JGE		0x30
+#define		BPF_JSET        0x40
+#define BPF_SRC(code)   ((code) & 0x08)
+#define		BPF_K		0x00
+#define		BPF_X		0x08
+
+#ifndef BPF_MAXINSNS
+#define BPF_MAXINSNS 4096
+#endif
+
+#endif /* __LINUX_BPF_COMMON_H__ */