[JuliaLowering] Add support for `Expr(:loopinfo, ...)` (#60410)
Very trivial change, but this is enough to get Statistics precompiling.
I also confirmed that we see the expected performance delta on our
[performance-tips example](https://docs.julialang.org/en/v1/manual/performance-tips/#man-performance-annotations):
```julia
julia> timeit(1000, 1000)
GFlop/sec = 3.918357111230404
GFlop/sec (SIMD) = 39.943280541630884
```
