ada: Constraint error not raised in ACATS test c413007

ada: Constraint error not raised in ACATS test c413007

The Constraint_Error exception is not raised when a subprogram
is called using prefix notation, and the prefix of the call is
an access-to-subprogram type with a null value. This new check
is enabled by switch -gnatd_P

gcc/ada/ChangeLog:

	* gen_il-fields.ads: New node field (Is_Expanded_Prefixed_Call).
	* gen_il-gen-gen_nodes.adb: New semantic field for N_Function_Call
	and N_Procedure_Call_Statement nodes.
	* sem_ch4.adb (Complete_Object_Operation): Mark the rewritten node
	with the Is_Expanded_Prefixed_Call flag.
	* sem_res.adb (Check_Prefixed_Call): Code cleanup and addition of
	documentation.
	(Resolve_Actuals): Add a null-exclusion check on the
	prefix of the call when it is an access-type.
	* sinfo.ads: Adding new semantic flag (Is_Expanded_Prefixed_Call)
	to N_Function_Call and N_Procedure_Call_Statement nodes.
	* debug.adb: Adding documentation for switch d_P.