Allow odsign to stop itself.

Carve out a label for the property, and allow odsign to set it.

Bug: 194334176
Test: no denials
Change-Id: I9dafefabc27c679ed9f36e617e824f44f3b16bbd
diff --git a/private/property.te b/private/property.te
index 49d18ee..3e48962 100644
--- a/private/property.te
+++ b/private/property.te
@@ -37,6 +37,7 @@
 system_internal_prop(verity_status_prop)
 system_internal_prop(zygote_wrap_prop)
 system_internal_prop(ctl_mediatranscoding_prop)
+system_internal_prop(ctl_odsign_prop)
 
 ###
 ### Neverallow rules