Fix google-explicit-constructor warnings in frameworks/base

* Add explicit keyword to conversion constructors.
* Add NOLINT to implicit conversion constructors.

Bug: 28341362
Test: build with clang-tidy
Change-Id: Ie4d37072ab57d1662d18db4de1c8577247f43337
diff --git a/libs/hwui/LayerCache.h b/libs/hwui/LayerCache.h
index 7d17b9b..94babf4 100644
--- a/libs/hwui/LayerCache.h
+++ b/libs/hwui/LayerCache.h
@@ -104,7 +104,7 @@
             mHeight = Layer::computeIdealHeight(layerHeight);
         }
 
-        LayerEntry(Layer* layer):
+        explicit LayerEntry(Layer* layer):
             mLayer(layer), mWidth(layer->getWidth()), mHeight(layer->getHeight()) {
         }