mac: Allow two sysctl-reads to common.sb

These denials were observed in local testing.

Change-Id: Iccfdbdbe4d755ac954bf6757505ee583dd89fa53
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2404411Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805928}

sandbox/policy/mac/common.sb

@@ -199,10 +199,12 @@
   (sysctl-name "hw.vectorunit")
   (sysctl-name "kern.hostname")
   (sysctl-name "kern.maxfilesperproc")
+  (sysctl-name "kern.osproductversion")
   (sysctl-name "kern.osrelease")
   (sysctl-name "kern.ostype")
   (sysctl-name "kern.osvariant_status")
   (sysctl-name "kern.osversion")
+  (sysctl-name "kern.secure_kernel")
   (sysctl-name "kern.usrstack64")
   (sysctl-name "kern.version")
   (sysctl-name "sysctl.proc_cputype")