Fix g++ (13) warnings

[kiwifb]

This PR fix two gcc warnings for C++ standard methods deprecated since the C++11 standard.

• the first one fix is in ginac and the fix is copied from the upstream project
• the second fix is in farey.cpp

Fixes #34996

📝 Checklist

• The title is concise, informative, and self-explanatory.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[mkoeppe]

LGTM.

[vbraun]

On OSX I get

[sagelib-10.1.beta1]     sage/modular/arithgroup/farey.cpp:742:19: error: use of undeclared identifier 'bind'; did you mean 'find'?
[sagelib-10.1.beta1]                       bind(greater<int>(), _1, 0))/2;
[sagelib-10.1.beta1]                       ^~~~
[sagelib-10.1.beta1]                       find

[mkoeppe]

Is that with Xcode "g++"?

[kiwifb]

Looking at the C++ doc, it may need to be std::bind to be fully correct. https://en.cppreference.com/w/cpp/utility/functional/bind

[github-actions]

Documentation preview for this PR (built with commit ce15f1e; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[kiwifb]

Looking at the C++ doc, it may need to be std::bind to be fully correct. https://en.cppreference.com/w/cpp/utility/functional/bind

I now see there is using namespace std; at the beginning of the file, so not the problem.

[vbraun]

Yes thats with the Xcode gcc, e.g. BigSur:

buildbot-sage@bigsur-osx build % gcc --version
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
Apple clang version 13.0.0 (clang-1300.0.29.30)
Target: x86_64-apple-darwin20.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

[mkoeppe]

A change to farey was done in #37646.

[mkoeppe]

Rebased.
I don't know if this extra line in farey is necessary

[kiwifb]

And that's the bit Volker had problem with. I should redo the branch.

[kiwifb]

Rebased. I don't know if this extra line in farey is necessary

I would think it is, but it is only fatal if you are strict (which is a promised future behaviour).