init.rc: add seclabel to flash_recovery

Make sure flash_recovery is always running in the
install_recovery SELinux domain.

Change-Id: I9495eedd03f6b5dfcf2e78c03d1102f6032b327a
diff --git a/rootdir/init.rc b/rootdir/init.rc
index b3ccae1..153cdcf 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -612,6 +612,7 @@
 
 service flash_recovery /system/bin/install-recovery.sh
     class main
+    seclabel u:r:install_recovery:s0
     oneshot
 
 service racoon /system/bin/racoon