enable the multithreaded LeaderPicker on linux (#5043)
enable the multithreaded LeaderPicker on linux (#5043)

* enable the multithreaded leaderpicker on linux

* response to review
greglandrum/rdkit,bp-kelley/rdkit,greglandrum/rdkit,bp-kelley/rdkit,ptosco/rdkit,bp-kelley/rdkit,greglandrum/rdkit,greglandrum/rdkit,rdkit/rdkit,rdkit/rdkit,bp-kelley/rdkit,greglandrum/rdkit,ptosco/rdkit,ptosco/rdkit,greglandrum/rdkit,rdkit/rdkit,bp-kelley/rdkit,ptosco/rdkit,bp-kelley/rdkit,greglandrum/rdkit,bp-kelley/rdkit,ptosco/rdkit,greglandrum/rdkit,rdkit/rdkit,ptosco/rdkit,bp-kelley/rdkit,rdkit/rdkit,ptosco/rdkit,rdkit/rdkit,ptosco/rdkit,rdkit/rdkit,rdkit/rdkit