Description of problem: GlusterFS has no optional support for libtirpc, and patches like https://gitweb.gentoo.org/repo/gentoo.git/tree/sys-cluster/glusterfs/files/glusterfs-3.12.3-libtirpc.patch currently don't work ( see https://bugzilla.redhat.com/1519315 ).
I have already pushed a variant of that patch to master. I will push another patch to fix the issue once you have confirmed it works. I suggest you close this bug and reopen bug #1519315.