logd: add reinit command

- respond to SIGHUP
- respond to logd command "reinit"
- respond to logd --reinit
- reopens files on /data, eg: re-read of persistent properties

Bug: 19681572
Change-Id: Iadac58e6653f027cb7355497bd675eef376ce0a8
diff --git a/logd/LogBuffer.h b/logd/LogBuffer.h
index b0003de..86a2a2a 100644
--- a/logd/LogBuffer.h
+++ b/logd/LogBuffer.h
@@ -46,6 +46,7 @@
     LastLogTimes &mTimes;
 
     LogBuffer(LastLogTimes *times);
+    void init();
 
     void log(log_id_t log_id, log_time realtime,
              uid_t uid, pid_t pid, pid_t tid,