xserver-common 1.34: sync /etc/X11/Xsession.d/90xXWindowManager with x11-common(oe-core)

Without that fix environments like sato cannot start because
  they require x-session-manager to be started instead of
  x-window-manager.

Signed-off-by: Denis Carikli <denis@eukrea.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>