P3925 R0 RO 3-292 29.10.8.3 [simd.comparison] Make `basic_simd` a Regular Type (with Boolean `operator==`)

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P3925R0 RO 3-292 29.10.8.3 [simd.comparison] Make basic_simd a Regular Type (with Boolean operator==) (Darius Neațu, Andrei Alexandrescu, Lucian Radu Teodorescu, Radu Nichita)