Fixed classes with undefined constructor.

IterativeRobot and BinaryImage had no constructor
defined (and so would give linker errors).
Error just had an empty constructor defined,
so I switched to "=default".

Change-Id: Ia8efb4282928227878dfefeda58ccb8cf06aabb2

wpilibc/wpilibC++/src/ErrorBase.cpp

@@ -16,10 +16,6 @@
 
 priority_mutex ErrorBase::_globalErrorMutex;
 Error ErrorBase::_globalError;
-/**
- * @brief Initialize the instance status to 0 for now.
- */
-ErrorBase::ErrorBase() {}
 
 /**
  * @brief Retrieve the current error.