[Ada] Put_Image: Enable for access-to-subprogram types

[Ada] Put_Image: Enable for access-to-subprogram types

2020-06-15  Bob Duff  <duff@adacore.com>

gcc/ada/

	* libgnat/s-putima.ads, libgnat/s-putima.adb
	(Put_Image_Access_Subp, Put_Image_Access_Prot): New procedures
	for printing access-to-subprogram objects.  Remove an explicit
	" ", because Put_Image includes the annoying leading blank.
	* rtsfind.ads: Add new procedures in s-putima.
	* exp_put_image.adb: Call new procedures as appropriate.