Give tts service sysinfo syscall perms

As of
https://chromium-review.googlesource.com/c/chromium/src/+/2510736

the tts service, which runs a prebuilt containing tensorFlow, now asks for
sysinfo.

R=mpdenton@chromium.org

Test: patch the above change and makes sure the tts works.
Change-Id: If578d0bb6617390a5919ac33b4b04970a33da317
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2514759Reviewed-by: Matthew Denton <mpdenton@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823347}

sandbox/policy/linux/bpf_tts_policy_linux.cc

@@ -26,6 +26,8 @@ TtsProcessPolicy::~TtsProcessPolicy() {}
 
 ResultExpr TtsProcessPolicy::EvaluateSyscall(int sysno) const {
   switch (sysno) {
+    case __NR_sysinfo:
+      return Allow();
     case __NR_sched_setscheduler:
       return RestrictSchedTarget(GetPolicyPid(), sysno);
     default: