[Bug c/96284] Outdated C features should be made errors with newer standards

[fw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96284
Bug 96284 depends on bug 106416, which changed state.

Bug 106416 Summary: -Wint-conversion should be an error, not a pedwarn
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106416

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED