Polynomial: Add overload which is only documented

[afabri]

Summary of Changes

Add code (a 3-liner) for a documented utility function. I did not add it to the testsuite as I have no idea for the parameter.

Release Management

• Affected package(s): Polynomial
• Issue(s) solved (if any): fix #8182
• License and copyright ownership: unchanged

[afabri]

@stla, could you please cherry-pick and use it to check.

[stla]

@stla, could you please cherry-pick and use it to check.

I have to download CGAL 6 in order to check a problem with RcppCGAL. But how can I "cherry-pick" your commit?

[sloriot]

Successfully tested in CGAL-6.0-Ic-242