traced_perf sepolicy tweaks

* allow shell to enable/disable the daemon via a sysprop
* don't audit signals, as some denials are expected
* exclude zygote from the profileable set of targets on debug builds.
  I've not caught any crashes in practice, but believe there's a
  possibility that the zygote forks while holding a non-whitelisted fd
  due to the signal handler.

Bug: 144281346
Merged-In: Ib237d4edfb40b200a3bd52e6341f13c4777de3f1
Change-Id: Ib237d4edfb40b200a3bd52e6341f13c4777de3f1
(cherry picked from commit 008465e5ec0603f9ce610584d42fba67e73ebfc5)
diff --git a/private/property_contexts b/private/property_contexts
index 6315c88..cba09a5 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -77,6 +77,7 @@
 persist.traced.enable   u:object_r:traced_enabled_prop:s0
 traced.lazy.            u:object_r:traced_lazy_prop:s0
 persist.heapprofd.enable u:object_r:heapprofd_enabled_prop:s0
+persist.traced_perf.enable u:object_r:traced_perf_enabled_prop:s0
 persist.vendor.overlay.  u:object_r:overlay_prop:s0
 ro.boot.vendor.overlay.  u:object_r:overlay_prop:s0
 ro.boottime.             u:object_r:boottime_prop:s0