[Ada] Tighten up semantic checking for protected subprogram declarations

[Ada] Tighten up semantic checking for protected subprogram declarations

2019-12-12  Steve Baird  <baird@adacore.com>

gcc/ada/

	* sem_ch6.adb
	(New_Overloaded_Entity.Check_Conforming_Paramters): Add new
	Conformance_Type parameter. With the value of
	Subtype_Conformant, the behavior of Check_Conforming_Parameters
	is unchanged.  The call in Matching_Entry_Or_Subprogram to
	instead passes in Type_Conformant. This corresponds to the use
	of "type conformant" in Ada RM 9.4(11.4/3).
	(New_Overloaded_Entity.Has_Matching_Entry_Or_Subprogram): Add
	new Normalized_First_Parameter_Type function to help in ignoring
	the distinction between protected and access-to-protected first
	parameters when checking prefixed-view profile matching. Replace
	computations of the type of the first parameter with calls to
	this function as appropriate.

From-SVN: r279303