Since Xen 4.11 is imported into ports, sysutils/xen-tools was renamed to sysutils/xen-tools47 and sysutils/xen-tools11 was added. This causes 'make index' to fail because it cannot find sysutils/xen-tools, which is a dependency of libvirt.
A commit references this bug: Author: novel Date: Thu Jul 26 15:44:57 UTC 2018 New revision: 475383 URL: https://svnweb.freebsd.org/changeset/ports/475383 Log: devel/libvirt: fix xen-tools dependency sysutils/xen-tools was moved to sysutils/xen-tools47, so update dependency accordingly. PR: 230041 Reported by: Ting-Wei Lan Changes: head/devel/libvirt/Makefile
(In reply to commit-hook from comment #1) Thanks for reporting that, should be fixed now.