Add a platform-specific syscall number iterator.

sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc

Index: sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc
diff --git a/sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc b/sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc
index 1422b5918d9a2d875bd5366a30f27a365995ac16..ffda1a85f20cc73da68fbd428ef7c2acf3387595 100644
--- a/sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc
+++ b/sandbox/linux/seccomp-bpf/sandbox_bpf_unittest.cc
@@ -46,6 +46,11 @@ ErrorCode BlacklistNanosleepPolicy(int sysno) {
     // FIXME: we should really not have to do that in a trivial policy
     return ErrorCode(ENOSYS);
   }
+#if defined(__arm__)
+  if (!Sandbox::isArmPrivateSyscall(sysno)) {
+    return ErrorCode(ENOSYS);
+  }
+#endif
   switch (sysno) {
     case __NR_nanosleep:
       return ErrorCode(EACCES);
@@ -105,6 +110,11 @@ ErrorCode BlacklistNanosleepPolicySigsys(int sysno) {
     // FIXME: we should really not have to do that in a trivial policy
     return ErrorCode(ENOSYS);
   }
+#if defined(__arm__)
+  if (!Sandbox::isArmPrivateSyscall(sysno)) {
+    return ErrorCode(ENOSYS);
+  }
+#endif
   switch (sysno) {
     case __NR_nanosleep:
       return Sandbox::Trap(EnomemHandler,