v.pref: allow for -os wasm32_emscripten and filtering `_d_wasm32_em…
#9387
Run time
Learn about OS # on GitHub Actions| Job | Run time |
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| 3m 47s | |
| 44m 25s | |
| 2h 53m 32s | |
| 55m 9s | |
| 2h 11m 45s | |
| 8h 59m 29s |