ada: Fix crash on declare expression in contract on access to subprogram type

As documented at the end of gen_il-gen-gen_entities.adb, E_Subprogram_Type
is part of Scope_Kind but, unlike what is said, it lacks Scope_Depth_Value.

gcc/ada/ChangeLog:

	* gen_il-gen-gen_entities.adb (E_Subprogram_Type): Add the missing
	Scope_Depth_Value field.
1 file changed