make simd loop over ranges perform better

[KristofferC]

Fixes #27773 (and likely the sumlinear_view benchmarks in #27030)

julia> function perf_sumlinear_view(A)
           s = zero(eltype(A))
           @inbounds @simd for I in 1:length(A)
               val = view(A, I)
               s += val[]
           end
           return s
       end
perf_sumlinear_view (generic function with 1 method)

julia> A = 1:1000000
1:1000000

julia> using BenchmarkTools

julia> @btime perf_sumlinear_view(A)
  110.620 μs (1 allocation: 16 bytes)
500000500000

julia> Base.firstindex(::UnitRange) = 1

julia> @btime perf_sumlinear_view(A)
  28.288 ns (1 allocation: 16 bytes)
500000500000

Apparently firstindex(::UnitRange) is right now too complex to see through. Arguably it would be better to try to figure out why it cannot be folded but it is a quite deep chain of calls...

Regression introduced in #27038 (with no Nanosoldier run, perhaps it was nonfunctional at the time)

[KristofferC]

@nanosoldier runbenchmarks(ALL, vs = ":master")

[nanosoldier]

Your benchmark job has completed - possible performance regressions were detected. A full report can be found here. cc @ararslan

[KristofferC]

Some bonus SIMD stuff improvements in there too. Unexpected, but I'll take it.