Add persist.heapprofd.enable property.

This is analoguous to what Perfetto does with persist.traced.enable.

Test: m
Test: flash walleye
Test: setprop persist.heapprofd.enable 1
      setprop persist.heapprofd.enable 0

Change-Id: I997272ef8c6fe078aca2388ed0cf2ecc3de612a5
diff --git a/private/property_contexts b/private/property_contexts
index adede99..5660d98 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -64,6 +64,7 @@
 persist.service.bdroid. u:object_r:bluetooth_prop:s0
 persist.security.       u:object_r:system_prop:s0
 persist.traced.enable   u:object_r:traced_enabled_prop:s0
+persist.heapprofd.enable u:object_r:heapprofd_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