logd: start cleaning up LogReaderThread

1) We can use real member functions with std::thread and
   std::function, so use those instead of the 'me' pointer.
2) Don't expose member variables directly.
3) Rename and document member variables, since all of their references
   are being touched anyway.

Test: logging unit tests
Change-Id: I9a357a3ea8691433d58687c95356b984b83e9c36
diff --git a/logd/LogKlog.cpp b/logd/LogKlog.cpp
index edd326a..5788ada 100644
--- a/logd/LogKlog.cpp
+++ b/logd/LogKlog.cpp
@@ -819,7 +819,7 @@
 
     // notify readers
     if (rc > 0) {
-        reader->notifyNewLog(static_cast<log_mask_t>(1 << LOG_ID_KERNEL));
+        reader->notifyNewLog(static_cast<unsigned int>(1 << LOG_ID_KERNEL));
     }
 
     return rc;