segredomap: only do the tricky case with versionedCode
segredomap: only do the tricky case with versionedCode

I insist on the change from 6a6e7827661941adb4e353151febd13b801d8977

There were benchmarks from the futhark-benchmark suite that got much worse
performance becauase of the `|| newSegmentedRedomap` part (Crystal, N-Body,
MRI-Q).

diku-dk/futhark,ihc/futhark,ihc/futhark,HIPERFIT/futhark,ihc/futhark,HIPERFIT/futhark,diku-dk/futhark,HIPERFIT/futhark,diku-dk/futhark,diku-dk/futhark,diku-dk/futhark