[v3 PATCH] Make optional's comparisons be two-parameter templates.

[Jonathan Wakely]

On 19/02/17 17:53 +0200, Ville Voutilainen wrote:
>This has not been adopted by LEWG/LWG yet, but was submitted
>as a proposed resolution for a new LWG issue; optional<const T> can't
>current be compared to a T, and an optional<T> can't be compared
>to something non-T that is comparable to a T. This approach fixes
>both of those problems, allowing optional's comparisons to actually
>work like the comparisons of the underlying type.
>
>Tested on Linux-x64.

Please mention LWG 2934 in the changelog. OK for trunk, thanks.