Fix import in quantile-generator
Fix import in quantile-generator

This was forgotten in 92b396d6.

Replaces #547.

dbeyer/benchexec,sosy-lab/benchexec,dbeyer/benchexec,ultimate-pa/benchexec,ultimate-pa/benchexec,sosy-lab/benchexec,sosy-lab/benchexec,sosy-lab/benchexec,ultimate-pa/benchexec,ultimate-pa/benchexec,ultimate-pa/benchexec,ultimate-pa/benchexec,dbeyer/benchexec,dbeyer/benchexec,sosy-lab/benchexec,sosy-lab/benchexec