c++: testsuite: Remove testsuite_tr1.h includes

c++: testsuite: Remove testsuite_tr1.h includes

This patch removes the testsuite_tr1.h dependency from g++.dg/ext/is_*.C
tests since the header is supposed to be used only by libstdc++, not
front-end.  This also includes test code consistency fixes.

For the record this fixes the test failures reported at
https://gcc.gnu.org/pipermail/gcc-patches/2023-December/641058.html

gcc/testsuite/ChangeLog:

	* g++.dg/ext/is_array.C: Remove testsuite_tr1.h.  Add necessary
	definitions accordingly.  Tweak macros for consistency across
	test codes.
	* g++.dg/ext/is_bounded_array.C: Likewise.
	* g++.dg/ext/is_function.C: Likewise.
	* g++.dg/ext/is_member_function_pointer.C: Likewise.
	* g++.dg/ext/is_member_object_pointer.C: Likewise.
	* g++.dg/ext/is_member_pointer.C: Likewise.
	* g++.dg/ext/is_object.C: Likewise.
	* g++.dg/ext/is_reference.C: Likewise.
	* g++.dg/ext/is_scoped_enum.C: Likewise.

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
Reviewed-by: Patrick Palka <ppalka@redhat.com>
Reviewed-by: Jason Merrill <jason@redhat.com>