rescue: Link libzutil after libzfs.

libzfs depends on symbols defined in libzutil. For static linking
ld.bfd is less forgiving than lld, so rescue was failing to link when
using ld.bfd due to unresolved symbols from libzutil used by libzfs.

Reviewed by: imp, kib, emaste
Differential Revision: https://reviews.freebsd.org/D36811