libxshmfence: update to 1.3.1.

Alan Coopersmith (6):
      Update README for gitlab migration
      Update configure.ac bug URL for gitlab migration
      Build xz tarballs instead of bzip2
      Fix spelling/wording issues
      gitlab CI: add a basic build test
      libxshmfence 1.3.1

Jan Beich (2):
      alloc: prefer atomic close-on-exec without O_TMPFILE as well
      alloc: prefer SHM_ANON on FreeBSD a la memfd_create

(wiz)