Early crash of servicemanager shouldn't start apexd

If servicemanager crashes when apexd isn't started yet, apexd shouldn't
be started. Otherwise, apexd will start much earlier than it is supposed
to be. It can cause various issues because apexd has many assumptions
around it (like some directories must have been created, etc.).

Adding `--only-if-running` ensures that.

Bug: N/A
Test: inject an error in servicemanager and see if apexd is not started
upon the servicemanager crash

Change-Id: I0b20a31115aaf7607cc0340e02183871e60d4178
diff --git a/cmds/servicemanager/servicemanager.rc b/cmds/servicemanager/servicemanager.rc
index 3bd6db5..4f92b3a 100644
--- a/cmds/servicemanager/servicemanager.rc
+++ b/cmds/servicemanager/servicemanager.rc
@@ -5,7 +5,7 @@
     critical
     file /dev/kmsg w
     onrestart setprop servicemanager.ready false
-    onrestart restart apexd
+    onrestart restart --only-if-running apexd
     onrestart restart audioserver
     onrestart restart gatekeeperd
     onrestart class_restart --only-enabled main