Put setChildren debug log in DEBUG clause

Summary:
Missed wrapping this previously :x
Closes https://github.com/facebook/react-native/pull/8930

Reviewed By: foghina

Differential Revision: D3593226

Pulled By: astreet

fbshipit-source-id: aea05a6fe7a806d0e31bb486d3de90fe18f2c15f

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModule.java

@@ -264,9 +264,11 @@ public class UIManagerModule extends ReactContextBaseJavaModule implements
   public void setChildren(
     int viewTag,
     ReadableArray childrenTags) {
-    FLog.d(
-        ReactConstants.TAG,
-        "(UIManager.setChildren) tag: " + viewTag + ", children: " + childrenTags);
+    if (DEBUG) {
+      FLog.d(
+          ReactConstants.TAG,
+          "(UIManager.setChildren) tag: " + viewTag + ", children: " + childrenTags);
+    }
     mUIImplementation.setChildren(viewTag, childrenTags);
   }