DEVELOPMENT_BUILDでもいける. [参考]http://qiita.com/rodostw/items/39183e62ed2a1f52f690

Debug.cs

#if !UNITY_EDITOR
#define DEBUG_LOG_OVERWRAP
#endif

using UnityEngine;

#if DEBUG_LOG_OVERWRAP
public static class Debug
{
	static public void Break(){
		if( IsEnable() )    UnityEngine.Debug.Break();
	}
	
	static public void Log( object message ){
		if( IsEnable() ){
			UnityEngine.Debug.Log( message );
		}
	}
	static public void Log( object message, Object context ){
		if( IsEnable() ) {
			UnityEngine.Debug.Log( message, context );
		}
	}
	
	static bool IsEnable(){ 
#if DEVELOPMENT_BUILD
		return true;
#endif
		return false;
	}
}
#endif