[clang] [clang] Allow extra semicolons inside classes also in C++ pedantic mode. (PR #172209)

[Corentin Jabot via cfe-commits]

https://github.com/cor3ntin commented:

Given that the change was made in a core issue - therefore allowing us to backport it, my inclination would be to remove the compatibility warnings all together and just emit a non-extension warning in all language modes. I suspect it would be more useful to users

WDYT @shafik @erichkeane ?

https://github.com/llvm/llvm-project/pull/172209