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/Dither.h b/libs/hwui/Dither.h
index b589b80..6af3e83 100644
--- a/libs/hwui/Dither.h
+++ b/libs/hwui/Dither.h
@@ -37,7 +37,7 @@
  */
 class Dither {
 public:
-    Dither(Caches& caches);
+    explicit Dither(Caches& caches);
 
     void clear();
     void setupProgram(Program& program, GLuint* textureUnit);