[clang] [Clang] Add -fwrapv-pointer flag (PR #122486)

[Nico Weber via cfe-commits]

nico wrote:

We (chromium) turned on fwrapv due to the pointer changes, and it had a bit of a perf hit. We'd probably switch to this, hoping it'd address the perf issues at least some.

Matching gcc's behavior for -f flags both compilers have also makes sense, IMHO.

https://github.com/llvm/llvm-project/pull/122486