wide-int: Fix build with gcc < 12 or clang++ [PR111787]

wide-int: Fix build with gcc < 12 or clang++ [PR111787]

While my wide_int patch bootstrapped/regtested fine when I used GCC 12
as system gcc, apparently it doesn't with GCC 11 and older or clang++.
For GCC before PR96555 C++ DR1315 implementation the compiler complains
about template argument involving template parameters, for clang++ the
same + complains about missing needs_write_val_arg static data member
in some wi::int_traits specializations.

2023-10-12  Jakub Jelinek  <jakub@redhat.com>

	PR bootstrap/111787
	* tree.h (wi::int_traits <unextended_tree>::needs_write_val_arg): New
	static data member.
	(int_traits <extended_tree <N>>::needs_write_val_arg): Likewise.
	(wi::ints_for): Provide separate partial specializations for
	generic_wide_int <extended_tree <N>> and INL_CONST_PRECISION or that
	and CONST_PRECISION, rather than using
	int_traits <extended_tree <N> >::precision_type as the second template
	argument.
	* rtl.h (wi::int_traits <rtx_mode_t>::needs_write_val_arg): New
	static data member.
	* double-int.h (wi::int_traits <double_int>::needs_write_val_arg):
	Likewise.