Does not build on iOS

[johnnyw]

Attempting to build a rodio-dependent static library for iOS using lipo yields the following error:

error: failed to run custom build command for `coreaudio-sys v0.2.5`

Caused by:
  process didn't exit successfully: `/Users/johnwatson/Projects/rodio-demo/target/release/build/coreaudio-sys-ff45525eed014540/build-script-build` (exit code: 101)
--- stdout
cargo:rerun-if-env-changed=COREAUDIO_SDK_PATH
cargo:rustc-link-lib=framework=AudioUnit
cargo:rustc-link-lib=framework=CoreAudio
cargo:rerun-if-env-changed=BINDGEN_EXTRA_CLANG_ARGS
cargo:warning=couldn't execute `llvm-config --prefix` (error: No such file or directory (os error 2))
cargo:warning=set the LLVM_CONFIG_PATH environment variable to the full path to a valid `llvm-config` executable (including the executable itself)

It looks like there may be a similar/related open issue in the repo for coreaudio-sys? RustAudio/coreaudio-sys#29

[est31]

I'd say this is a dupe of the bug you linked. Also, it's a build failure in the coreaudio-sys crate so it's better to report it there. Thanks!