[Ada] Missing implicit interface type conversion

[Ada] Missing implicit interface type conversion

The compiler skips adding an implicit type conversion when the interface
type is visible through a limited-with clause.

No small reproducer available.

2019-07-10  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* exp_ch6.adb (Is_Class_Wide_Interface_Type): New subprogram.
	(Expand_Call_Helper): Handle non-limited views when we check if
	any formal is a class-wide interface type.
	* exp_disp.adb (Expand_Interface_Actuals): Handle non-limited
	views when we look for interface type formals to force "this"
	displacement.

From-SVN: r273328