ada: Fix SPARK test failures caused by new handling of inherited class-wide pre/post

ada: Fix SPARK test failures caused by new handling of inherited class-wide pre/post

The revised handling of inherited class-wide pre/postconditions (for
properly implementing the rules of RM 6.1.1(7/5)) broke two SPARK tests
(N709-001__contracts and V516-041__private_ownership). This change fixes
that, by refining the test for detecting formal parameters used as actuals
in calls to primitive functions, as well as adding handling for 'Result
attributes given as actuals in such calls.

gcc/ada/ChangeLog:

	* exp_util.adb (Call_To_Parent_Dispatching_Op_Must_Be_Mapped): Replace
	test of Covers with test of Is_Controlling_Formal. Add handling for
	'Result actuals. Remove Actual_Type and its uses.