[llvm] [llvm] Add Trusty OSType (PR #210119)

[Wes Carvalho via llvm-commits]

SilensAngelusNex wrote:

I have [another change](https://github.com/llvm/llvm-project/commit/5e0f139188243fc2a52b9a8c2b5cec06ba896c27) (that depends on this one) which adds `TrustyTargetInfo`s for our supported archs. It _is_ just adding a macro define.

Is that config file something that we'd upstream to clang, or would that remain in the Trusty project? Because we have `<arch>-unknown-trusty` targets upstreamed in `rustc` ([armv7](https://github.com/rust-lang/rust/blob/main/compiler/rustc_target/src/spec/targets/armv7_unknown_trusty.rs) [aarch64](https://github.com/rust-lang/rust/blob/main/compiler/rustc_target/src/spec/targets/aarch64_unknown_trusty.rs) [x86_64](https://github.com/rust-lang/rust/blob/main/compiler/rustc_target/src/spec/targets/x86_64_unknown_trusty.rs)); I'd like to change their `llvm_target` to use the `trusty` OS instead of `unknown` and IIUC I wouldn't be able to do that with a project local config (or with any config file?).

https://github.com/llvm/llvm-project/pull/210119