The previous code was tentatively written to run either in a Fibers context or
in a non-Fibers context. Drop the non-Fibers code since this always runs
within ‘shepherd’, which is fiberized.
* gnu/build/secret-service.scm (with-modules): Remove.
(wait-for-readable-fd): Rewrite using regular Fibers operations.
(secret-service-send-secrets): Use ‘SOCK_NONBLOCK’. Simplify ‘sleep’ binding.
Change-Id: Ic05d0bc54e6d2df89b6602bc716402067c845792