MAINT: Remove references to missing files from install.

The following directories and files have been moved or deleted

    numpy/lib/benchmarks
    numpy/f2py/docs
    numpy/f2py/f2py.1

This PR removes references to them from the relevant setup.py files.

Closes #5010.
Merge pull request #5021 from charris/remove-missing-files-from-setup

MAINT: Remove references to missing files from install.