Refactoring: simplify axis label generation.
Refactoring: simplify axis label generation.

michkot/benchexec,ultimate-pa/benchexec,cheshire/benchexec,IljaZakharov/benchexec,michkot/benchexec,sosy-lab/benchexec,ultimate-pa/benchexec,ultimate-pa/benchexec,IljaZakharov/benchexec,bjowac/impara-benchexec,dbeyer/benchexec,dbeyer/benchexec,sosy-lab/benchexec,martin-neuhaeusser/benchexec,ultimate-pa/benchexec,martin-neuhaeusser/benchexec,sosy-lab/benchexec,martin-neuhaeusser/benchexec,dbeyer/benchexec,cheshire/benchexec,bjowac/impara-benchexec,michkot/benchexec,dbeyer/benchexec,ultimate-pa/benchexec,IljaZakharov/benchexec,bjowac/impara-benchexec,sosy-lab/benchexec,sosy-lab/benchexec,cheshire/benchexec,martin-neuhaeusser/benchexec,ultimate-pa/benchexec,IljaZakharov/benchexec,sosy-lab/benchexec