Fix google-explicit-constructor warnings in surfaceflinger.

* Add explicit keyword to conversion constructors,
  or use NOLINT for implicit converters.
Bug: 28341362
Test: build with WITH_TIDY=1

Change-Id: I94f511c3be31dc22022db6466ee9ed0c6be2bc8e
diff --git a/services/surfaceflinger/EventLog/EventLog.h b/services/surfaceflinger/EventLog/EventLog.h
index 5207514..efc5d70 100644
--- a/services/surfaceflinger/EventLog/EventLog.h
+++ b/services/surfaceflinger/EventLog/EventLog.h
@@ -52,7 +52,7 @@
         bool mOverflow;
         char mStorage[STORAGE_MAX_SIZE];
     public:
-        TagBuffer(int32_t tag);
+        explicit TagBuffer(int32_t tag);
 
         // starts list of items
         void startList(int8_t count);