* Remove support for linking arclite
Darwin no longer uses arclite and it's no longer distributed
in the macOS SDKs.
This leaves the options -link-objc-runtime and -no-link-objc-runtime
in place, but strips out all the logic that actually used them.
* Remove a dead function
* Warn if `-link-objc-runtime` is used
* Update tests to not look for arclite library
* Add an explicit test for the deprecation warning
* Move the macOS-only -link-objc-runtime test to a separate test file
