There's probably no reason to restrict it to Linux.
I can't test directly, but Hombrew does have the package.
My intention is to build knot-resolver for Darwin as well.
(And update liburcu to 0.8.4 according to release notes for lttng 2.4.x.)
In addition to new features and bug fixes, version 2.4.x is needed to build
against Linux 3.12 (our new stable kernel).