Fix google-explicit-constructor warnings in frameworks/rs.

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

 Bug: 28341362
 Test: build with clang-tidy

Change-Id: If5114de668c1c8946b8fca9cee4b2b14f95be5f1
diff --git a/rsScriptIntrinsic.h b/rsScriptIntrinsic.h
index 9b4f9d3..cd8253d 100644
--- a/rsScriptIntrinsic.h
+++ b/rsScriptIntrinsic.h
@@ -30,7 +30,7 @@
 
     ObjectBaseRef<const Element> mElement;
 
-    ScriptIntrinsic(Context *);
+    explicit ScriptIntrinsic(Context *);
     ~ScriptIntrinsic() override;
 
     bool init(Context *rsc, RsScriptIntrinsicID iid, Element *e);