Start serial console at the 'init' trigger

Start the serial console at the 'init' trigger instead of much later
when property triggers happen.  This will help debugging early boot
issues.

Test: serial console starts early for a userdebug build
Test: serial console still doesn't start on a user build
Change-Id: I7112a8e7171c9fa865c8787c9a3d14515bc59478
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 97f1854..bb36139 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -868,6 +868,8 @@
     chmod 0773 /data/misc/trace
     # Give reads to anyone for the window trace folder on debug builds.
     chmod 0775 /data/misc/wmtrace
+
+on init && property:ro.debuggable=1
     start console
 
 service flash_recovery /system/bin/install-recovery.sh