[clang] [Clang] Remove AArch64TargetInfo::setArchFeatures (PR #146107)

[Jonathan Thackray via cfe-commits]

jthackray wrote:

Thanks @sdesmalen-arm. We'd like to move all these kinds of dependencies into tablegen, and have nothing encoded in C++, and I've got a (half-started) diff to do this, but haven't found time to prioritise it yet. Your change helps, though! LGTM.

https://github.com/llvm/llvm-project/pull/146107