Non-SFI NaCl: Allow openat system call to gracefully fail on BareMetal seccomp-bpf.

components/nacl/loader/nonsfi/nonsfi_sandbox.cc

Index: components/nacl/loader/nonsfi/nonsfi_sandbox.cc
diff --git a/components/nacl/loader/nonsfi/nonsfi_sandbox.cc b/components/nacl/loader/nonsfi/nonsfi_sandbox.cc
index 35ee417d2051e2ddfb720f879e7d0e5c86ce8382..b5fe899746c3bc7a70b62193ccc693766e917216 100644
--- a/components/nacl/loader/nonsfi/nonsfi_sandbox.cc
+++ b/components/nacl/loader/nonsfi/nonsfi_sandbox.cc
@@ -162,8 +162,10 @@ bool IsGracefullyDenied(int sysno) {
     // tcmalloc calls madvise in TCMalloc_SystemRelease.
     case __NR_madvise:
     // EPERM instead of SIGSYS as glibc tries to open files in /proc.
+    // openat via opendir via get_nprocs_conf and open via get_nprocs.
     // TODO(hamaji): Remove this when we switch to newlib.
     case __NR_open:
+    case __NR_openat:
     // For RunSandboxSanityChecks().
     case __NR_ptrace:
     // glibc uses this for its pthread implementation. If we return