The proposed resolution for this library issue simplifies the
constraints for compare_three_way, ranges::equal_to, ranges::less etc.
so that they do not work with types which are convertible to pointers
but which fail to meet the usual syntactic requirements for the
comparisons.

This affects the example in PR libstdc++/93628 but doesn't fix the
problem described in that report.

libstdc++-v3/ChangeLog:

	* include/bits/ranges_cmp.h (__eq_builtin_ptr_cmp): Remove.
	(ranges::equal_to, ranges::not_equal_to): Do not constrain
	with __eq_builtin_ptr_cmp.
	(ranges::less, ranges::greater, ranges::less_equal)
	(ranges::greater_equal): Do not constrain with
	__less_builtin_ptr_cmp.
	* libsupc++/compare (compare_three_way): Do not constrain with
	__3way_builtin_ptr_cmp.
	* testsuite/18_support/comparisons/object/builtin-ptr-three-way.cc: Moved to...
	* testsuite/18_support/comparisons/object/lwg3530.cc: ...here.
	* testsuite/20_util/function_objects/range.cmp/lwg3530.cc: New test.

Tested powerpc64le-linux. Committed to trunk.