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/DispSync.h b/services/surfaceflinger/DispSync.h
index 537c81b..2763e59 100644
--- a/services/surfaceflinger/DispSync.h
+++ b/services/surfaceflinger/DispSync.h
@@ -61,7 +61,7 @@
         virtual void onDispSyncEvent(nsecs_t when) = 0;
     };
 
-    DispSync(const char* name);
+    explicit DispSync(const char* name);
     ~DispSync();
 
     // reset clears the resync samples and error value.