Take advantage of C++20 and define only == and let the compiler define !=.
<rdar://problem/108958354>
Pull request: https://github.com/WebKit/WebKit/pull/13515
Committed 263758@main (6e8fa5269513): <https://commits.webkit.org/263758@main> Reviewed commits have been landed. Closing PR #13515 and removing active labels.