Fix google-explicit-constructor warnings in utils.

* Declare explicit conversion constructors.
* Use NOLINT(implicit) for implicit conversion constructors.

Bug: 28341362
Change-Id: I4fb58fa32aafc520b2ed862a05a8bdbfabbc6c35
Test: build with WITH_TIDY=1
diff --git a/include/utils/Condition.h b/include/utils/Condition.h
index a420185..5650598 100644
--- a/include/utils/Condition.h
+++ b/include/utils/Condition.h
@@ -54,7 +54,7 @@
     };
 
     Condition();
-    Condition(int type);
+    explicit Condition(int type);
     ~Condition();
     // Wait on the condition variable.  Lock the mutex before calling.
     status_t wait(Mutex& mutex);