sem_ch10.adb (Install_Withed_Unit): If the unit is a generic instance that is the parent of other generics...

	* sem_ch10.adb (Install_Withed_Unit): If the unit is a generic instance
	that is the parent of other generics, the instance body replaces the
	instance node.  Retrieve the instance of the spec, which is the one
	that is visible in clients and within the body.

From-SVN: r47906