[clang] [LifetimeSafety] Enable C support by default under -Wlifetime-safety (PR #224028)

[Corentin Jabot via cfe-commits]

cor3ntin wrote:

> is change enables lifetime safety for C when lifetime safety is enabled via `-Wlifetime-safety`. This warning is not being proposed to be enabled by default in Clang.

Thanks @usx95, this is a lot more reasonable than I thought it was (and yes, does not need an RFC)

https://github.com/llvm/llvm-project/pull/224028