ada: Fix regression of finalization primitive selection

ada: Fix regression of finalization primitive selection

A recent patch introduced a new flag to mark the types for which looking
up finalization primitives needs special handling. But there was one
place in Build_Derived_Record_Type where the flag was not set when it
should, which introduced a regression in some cases.

This patch adds the missing setting of the flag.

gcc/ada/ChangeLog:

	* sem_ch3.adb (Build_Derived_Record_Type): Set flag appropriately.