[Ada] Checking type invariants on in params of procedures, not functions (AI12-0044)

[Ada] Checking type invariants on in params of procedures, not functions (AI12-0044)

gcc/ada/

	* contracts.adb (Add_Invariant_And_Predicate_Checks): Relax the
	condition for doing invariant checks so that in-mode parameters
	of procedures are also checked (required by AI05-0289, and
	restricted to procedures by AI12-0044). This is done in a
	procedure's nested postconditions procedure.
	* exp_ch6.adb (Expand_Actuals): Also perform postcall invariant
	checks for in parameters of procedures (but not functions).
	Moved invariant-checking code to end of Expand_Actuals
	(including the nested function Is_Public_Subp).