content: bpf: exclude the syscalls if arm64

__NR_unlink is not defined on arm64.

BUG=None
R= mdempsky

Review URL: https://codereview.chromium.org/1424513005

Cr-Commit-Position: refs/heads/master@{#358579}
diff --git a/AUTHORS b/AUTHORS
index 7f0279c..498f6aec 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -632,6 +632,7 @@
 Zhuoyu Qian <[email protected]>
 Ziran Sun <[email protected]>
 Zoltan Herczeg <[email protected]>
+Zoltan Kuscsik <[email protected]>
 Zsolt Borbely <[email protected]>
 Yongha Lee <[email protected]>
 方觉 (Fang Jue) <[email protected]>