ada: Fix internal error on expression function with Refined_Post aspect

ada: Fix internal error on expression function with Refined_Post aspect

This occurs when the expression function calls a protected function and the
-gnata switch is specified, because the compiler wrongly freezes the called
function when analyzing the expression function, a fallout of the wrapping
scheme used for the Post and Refined_Post aspects.

gcc/ada/

	* sem_res.adb (Resolve_Call): When the target is an entity, do not
	freeze it if the current scope is the inner wrapper function built
	for an expression function with a Post or Refined_Post aspect.