comment out more unused procedures in scheme.scm benchmark

[JeffBezanson]

Hi there, nice project! I've been having a lot of fun with these benchmarks.

This change removes more references to procedures that might not be defined in the scheme benchmark, allowing it to run in more systems.

[ecraven]

Do these influence any results? They were like this when I copied the benchmarks, I'd rather not touch the actual benchmark code unless necessary ;)

[JeffBezanson]

I don't believe so. In femtolisp, I got undefined variable errors for all of these, and commenting them made the benchmark run, so I assume that means the benchmark doesn't use these procedures. But if you prefer I can define stubs for these in the femtolisp prelude instead.