[clang] [-Wunsafe-buffer-usage] Warning Libc functions (PR #101583)

[Ziqing Luo via cfe-commits]

ziqingluo-90 wrote:

> There needs to be a flag to opt out of this to not break everybody who is currently using unsafe-buffer-usage. #105383 seems to do that, but it really should be in this same PR. Can this be reverted and relanded with the flag?

ok, will do

https://github.com/llvm/llvm-project/pull/101583