Better message for GCC OLD ABI COMPATIBILITY

[Ignition]

Changelog: Fix: Better message for gcc warning of libstdc++ at default profile detection
Docs: omit

A simple usability and quality of life improvement. It is better to copy and paste a command given to you, rather than manual editing of a file.

Close #5273

[CLAassistant]

All committers have signed the CLA.

[memsharded]

Hi @Ignition

There were failing tests, because that message was being tested. I have done some changes in https://github.com/memsharded/conan/tree/feature/gcc_msg

• Fix the broken tests
• Added to the message a note about editing manually with the full path, as the suggested message only works for profiles in the conan default cache location, but users can have profiles elsewhere.
• Fixed some minor pep8 warnings

I have tried to push those changes to your branch or do a PR to your branch, but Github won't allow me (it typically does). Please take my changes from my branch and apply them to yours, so CI is green.

Thanks for your contribution!

[memsharded]

Merged, to be released in 1.17, thanks!