Allow AID_RADIO to restart the ril-daemon.

This enhances robustness by allowing the Telephony Framework to restart
ril-daemon if it notices some catastrophic failure.

Added setprop ctl.restart.
Added ril-daemon to setprop control_perms and allow users/groups
with the AID_RADIO ID to control it.

Change-Id: I195abdd754a731ce0b77e8f71ab47fde8c3e7977
diff --git a/init/init.c b/init/init.c
index 709cc40..cd129c3 100755
--- a/init/init.c
+++ b/init/init.c
@@ -384,6 +384,9 @@
         msg_start(arg);
     } else if (!strcmp(msg,"stop")) {
         msg_stop(arg);
+    } else if (!strcmp(msg,"restart")) {
+        msg_stop(arg);
+        msg_start(arg);
     } else {
         ERROR("unknown control msg '%s'\n", msg);
     }