This combines the overloads for arrays with the non-array overloads,
using if-constexpr to choose between the cases, and also enforces the
following:

- ADL should only be used for class types and enumeration types.
- ranges::begin should be ill-formed for rvalue arrays.
- ranges::end should be ill-formed for rvalue arrays, unbounded
  arrays, and arrays of incomplete type.
- ranges::size should be ill-formed for unbounded arrays.

	* include/bits/range_access.h (ranges::begin): Combine array and
	non-array overloads into one function template. Only use ADL for
	classes and enums
	(ranges::end, ranges::size): Likewise. Make unbounded arrays
	ill-formed.
	(ranges::rbegin, ranges::rend): Only use ADL for classes and enums.
	Reformat _S_noexcept() functions to mirror operator() structure.
	* testsuite/std/ranges/access/begin.cc: Check incomplete array.
	* testsuite/std/ranges/access/end_neg.cc: New test.
	* testsuite/std/ranges/access/size.cc: Check array of incomplete type.
	* testsuite/std/ranges/access/size_neg.cc: New test.

This implements what the standard *should* say, not what's in the
current draft. I submitted a ballot comment about the unbounded arrays
part and have been talking to Casey Carter about cleaning up the spec
to match what this patch implements.

Tested powerpc64le-linux, committed to trunk.