sandbox: Fix RedirectToUserSpacePolicyWrapper

sandbox/linux/seccomp-bpf/sandbox_bpf.h

Index: sandbox/linux/seccomp-bpf/sandbox_bpf.h
diff --git a/sandbox/linux/seccomp-bpf/sandbox_bpf.h b/sandbox/linux/seccomp-bpf/sandbox_bpf.h
index 51f2f2469fffe4530fbdf5a9213fc34ad882eeb2..870e8a0d9cabde1bdfa159bb6dec19662e9f0775 100644
--- a/sandbox/linux/seccomp-bpf/sandbox_bpf.h
+++ b/sandbox/linux/seccomp-bpf/sandbox_bpf.h
@@ -130,6 +130,10 @@ class SANDBOX_EXPORT SandboxBPF {
   //   entire sandbox should be considered compromised.
   ErrorCode UnsafeTrap(Trap::TrapFnc fnc, const void* aux);
 
+  // UnsafeTraps require some syscalls to always be allowed.
+  // This helper function returns true for these calls.
+  static bool IsRequiredForUnsafeTrap(int sysno);
+
   // From within an UnsafeTrap() it is often useful to be able to execute
   // the system call that triggered the trap. The ForwardSyscall() method
   // makes this easy. It is more efficient than calling glibc's syscall()