Mark AbstractQ and LQPackedQ as non-fast_scalar_indexing

[tkf]

Their getindex are defined in terms of multiplications. So I guess it makes sense to mark them as non-fast_scalar_indexing?

function getindex(Q::AbstractQ, i::Integer, j::Integer)
    x = zeros(eltype(Q), size(Q, 1))
    x[i] = 1
    y = zeros(eltype(Q), size(Q, 2))
    y[j] = 1
    return dot(x, lmul!(Q, y))
end

--- https://github.com/JuliaLang/julia/blob/6eebbbe2d205f8116330a77ca5e15f4a356232db/stdlib/LinearAlgebra/src/qr.jl#L526-L532

getindex(A::LQPackedQ, i::Integer, j::Integer) =
    lmul!(A, setindex!(zeros(eltype(A), size(A, 2)), 1, j))[i]

--- https://github.com/JuliaLang/julia/blob/6eebbbe2d205f8116330a77ca5e15f4a356232db/stdlib/LinearAlgebra/src/lq.jl#L139-L140

[ChrisRackauckas]

Yes, good point!