Introduce linux_filter.h and replace #include <linux/filter.h>

sandbox/linux/system_headers/linux_seccomp.h

Index: sandbox/linux/system_headers/linux_seccomp.h
diff --git a/sandbox/linux/system_headers/linux_seccomp.h b/sandbox/linux/system_headers/linux_seccomp.h
index 40029c8efbbc663874f425e1550aace19286ad9e..3deb3d2253c0d84a503fb6651f43bbceec7c8866 100644
--- a/sandbox/linux/system_headers/linux_seccomp.h
+++ b/sandbox/linux/system_headers/linux_seccomp.h
@@ -5,8 +5,6 @@
 #ifndef SANDBOX_LINUX_SYSTEM_HEADERS_LINUX_SECCOMP_H_
 #define SANDBOX_LINUX_SYSTEM_HEADERS_LINUX_SECCOMP_H_
 
-#include <linux/filter.h>
-
 // The Seccomp2 kernel ABI is not part of older versions of glibc.
 // As we can't break compilation with these versions of the library,
 // we explicitly define all missing symbols.
@@ -67,13 +65,6 @@
 #define IPC_64                   0x0100
 #endif
 
-#ifndef BPF_MOD
-#define BPF_MOD                    0x90
-#endif
-#ifndef BPF_XOR
-#define BPF_XOR                    0xA0
-#endif
-
 // In order to build will older tool chains, we currently have to avoid
 // including <linux/seccomp.h>. Until that can be fixed (if ever). Rely on
 // our own definitions of the seccomp kernel ABI.