Corrected a typo in fussy warning:-Wredundant-delcs -> -Wredundant-decls

[Iximiel]

Description

As title

Target release

I would like my code to appear in release v2.10? If you ask, I can back port this to v2.8, it is just a single commit with 8 inverted letters that I can be rebased easily

Type of contribution

• [x] changes to code or doc authored by PLUMED developers, or additions of code in the core or within the default modules
• [ ] changes to a module not authored by you
• [ ] new module contribution or edit of a module authored by you

Copyright

• [x] I agree to transfer the copyright of the code I have written to the PLUMED developers or to the author of the code I am modifying.

• [ ] the module I added or modified contains a COPYRIGHT file with the correct license information. Code should be released under an open source license. I also used the command cd src && ./header.sh mymodulename in order to make sure the headers of the module are correct.

Tests

• [ ] I added a new regtest or modified an existing regtest to validate my changes.
• [ ] I verified that all regtests are passed successfully on GitHub Actions.

[GiovanniBussi]

Yes maybe it's a good idea to backport it.. Thanks!

[Iximiel]

@GiovanniBussi I rebased on v2.8 I would wait for the CI to finish in case something went haywire