xorg-server-source 2:1.18.4-0ubuntu0.2 (s390x binary) in ubuntu xenial

 This package provides original Debian (with Debian patches already
 applied, and autotools files updated) sources for the X.Org ('Xorg')
 X server shipped in a tarball. This enables other projects re-using
 X server codebase (e.g. VNC servers) to (re-)use officially
 Debian-supported version of the X xserver for their builds.
 .
 Unless you are building a software product using X server sources,
 you probably want xserver-xorg and/or xserver-xorg-core instead.