Prefer using the existing var over lists of supported architectures. Also re-enable two tests which appear not to have really needed SIMD support to pass, and two other tests that are no longer failing on ARMv7.
Pull request: https://github.com/WebKit/WebKit/pull/12504
Committed 262716@main (3096b28ff05a): <https://commits.webkit.org/262716@main> Reviewed commits have been landed. Closing PR #12504 and removing active labels.
<rdar://problem/107760577>