Rewrite ada_value_print_inner

Rewrite ada_value_print_inner

This rewrites ada_value_print_inner, introducing a new
ada_value_print_1, an analogue of ada_val_print_1.  Because it was
simple to do, this also converts ada_val_print_gnat_array to be
valued-based and updates the uses.

gdb/ChangeLog
2020-03-13  Tom Tromey  <tom@tromey.com>

	* ada-valprint.c (ada_val_print_gnat_array): Take a struct value;
	call common_val_print.
	(ada_val_print_1): Update.
	(ada_value_print_1): New function.
	(ada_value_print_inner): Rewrite.