servicemanager started property

If something starts before servicemanager does,
intelligently wait for servicemanager to start rather
than sleeping for 1s.

Bug: 239382640
Test: boot
Change-Id: If0380c3a1fce937b0939cd6137fcb25f3e47d14c
diff --git a/private/property_contexts b/private/property_contexts
index cd880d3..dd8849b 100644
--- a/private/property_contexts
+++ b/private/property_contexts
@@ -220,6 +220,9 @@
 # heapprofd properties
 heapprofd.              u:object_r:heapprofd_prop:s0
 
+# servicemanager properties
+servicemanager.ready    u:object_r:servicemanager_prop:s0 exact bool
+
 # hwservicemanager properties
 hwservicemanager.       u:object_r:hwservicemanager_prop:s0