c++: Fix printing of C++20 template parameter object [PR97014]

c++: Fix printing of C++20 template parameter object [PR97014]

No one is interested in the mangled name of the C++20 template parameter
object for a class NTTP.  So instead of printing

  required for the satisfaction of ‘positive<T::ratio>’ [with T = X<::_ZTAXtl5ratioLin1ELi2EEE>]

let's print

  required for the satisfaction of ‘positive<T::ratio>’ [with T = X<{-1, 2}>]

I don't think adding a test is necessary for this.

gcc/cp/ChangeLog:

	PR c++/97014
	* cxx-pretty-print.c (pp_cxx_template_argument_list): If the
	argument is template_parm_object_p, print its DECL_INITIAL.