Log Message:
libhighway: update to 1.2.0.

Convert to cmake/build.mk.

1.2.0

    Add InterleaveEven/InterleaveOdd, BitShuffle, GatherIndexNOr
    Add IsNegative, IfNegativeThenElseZero, IfNegativeThenZeroElse
    Add NEON_BF16, HWY_VERSION_GE/LT, HWY_EXPORT_T/HWY_DYNAMIC_DISPATCH_T
    Add PromoteInRangeTo/ConvertInRangeTo/DemoteInRangeTo
    Add Rol/Ror, RotateLeft/RotateLeftSame/RotateRightSame
    Add SatWidenMulPairwiseAccumulate, SatWidenMulAccumFixedPoint
    Add stats.h, bit_set.h, IsEitherNaN
    Add UI8/UI32/UI64 MulHigh, I64 MulEven/MulOdd/Mul128
    Add WidenMulAccumulate, MulEvenAdd, MulOddAdd
    contrib/bit_pack: support 32/64-bit lanes
    contrib/math: Add Exp2, Hypot
    contrib/matvec: Add MatVecAdd
    contrib/sort: Add VQ/HeapSelect, partial sort
    contrib/topology: add affinity, detect topology/cache size/CPU name
    Enable runtime dispatch for NEON/RVV, bazel modules, abort handler
    Remove DASSERT for negative Gather indices
    Support opting out of GUnit dependency
    Use SPR/ZEN4 bf16 dot product
    Known GCC 13 RVV issue: parts of sort_test and bit_pack_test disabled
    Known Clang RVV/QEMU issue: incorrect rounding mode in upper/lower halves

1.1.0

    Add BitCastScalar, DispatchedTarget, Foreach
    Add Div/Mod and MaskedDiv/ModOr, SaturatedAbs, SaturatedNeg
    Add InterleaveWholeLower/Upper, Dup128VecFromValues
    Add IsInteger, IsIntegerLaneType, RemoveVolatile, RemoveCvRef
    Add MaskedAdd/Sub/Mul/Div/Gather/Min/Max/SatAdd/SatSubOr
    Add MaskFalse, IfNegativeThenNegOrUndefIfZero, PromoteEven/OddTo
    Add ReduceMin/Max, 8-bit reductions, f16 <-> f64 conversions
    Add Span, AlignedArray, matrix-vector mul
    Add SumsOf2/4, I8 SumsOf8, SumsOfAdjQuadAbsDiff, SumsOfShuffledQuadAbsDiff
    Add ThreadPool, hierarchical profiler
    Build: use bazel_platforms
    Enable clang16 Arm/PPC runtime dispatch, F16 for GCC AVX3_SPR
    Extend Dot to f32*bf16, FMA to integer
    Fix: RVV 8-bit overflow, UB in vqsort, big-endian bugs, PPC HTM
    Improved codegen in various ops, fp16/bf16 tests and conversions
    New targets: HWY_Z14, HWY_Z15
    Test: add foreign_arch builders, CodeQL