* Restore the mono_jit_thread_attach signature to how it's in
the latest stable.
* Don't use the new attach/detach methods when using the dynamic
mono runtime, since the methods aren't available in any released
version of mono. Also XM doesn't support coop yet, so it's not
needed.
* And finally don't use the new attach/detach methods for anything
that isn't building using mono/master (iow only watchOS). This
should be changed once the rest of the products starts using
mono/master again.
Rolf Bjarne Kvinge