Bug 1536137 - Add getrusage to RDD policy. r=jld

Depends on D24190

Differential Revision: https://phabricator.services.mozilla.com/D25621

--HG--
extra : moz-landing-system : lando

security/sandbox/linux/SandboxFilter.cpp

@@ -1420,6 +1420,9 @@ class RDDSandboxPolicy final : public SandboxPolicyCommon {
 
   ResultExpr EvaluateSyscall(int sysno) const override {
     switch (sysno) {
+      case __NR_getrusage:
+        return Allow();
+
       CASES_FOR_fcntl:
         return Trap(FcntlTrap, nullptr);