[Ada] Spurious error passing access to class-wide interface type

[Ada] Spurious error passing access to class-wide interface type

The compiler reports an spurious error when the formal parameter of a
subprogram is an access to a class wide interface type and the actual
parameter is an allocator of an object covering such interface type.

2019-07-22  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* sem_res.adb (Resolve_Actuals): Replace code that displaces the
	pointer to an allocated object to reference its secondary
	dispatch table by a type conversion (which takes care of
	handling all cases).

gcc/testsuite/

	* gnat.dg/class_wide5.adb: New testcase.

From-SVN: r273690