Refactor startup to not require files in /etc/skel/

config/X11/Xsession.d/60virtualgl

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+if [ -z "${VGL_DISPLAY-}" ]; then
+	# Use the dummy X server if it is enabled
+	if [ "${ENABLE_XDUMMY:?}" = 'true' ]; then
+		export VGL_DISPLAY=:0.0
+	else
+		# Otherwise try to use the EGL backend
+		for card in /dev/dri/card*; do
+			if /opt/VirtualGL/bin/eglinfo -B "${card:?}" 2>/dev/null; then
+				export VGL_DISPLAY="${card:?}"
+				break
+			fi
+		done
+		# And fallback to DISPLAY if the EGL backend is not available
+		if [ -z "${VGL_DISPLAY-}" ] && [ -n "${DISPLAY-}" ]; then
+			export VGL_DISPLAY="${DISPLAY:?}"
+		fi
+	fi
+fi

config/skel/.xsession

@@ -1,3 +0,0 @@
-#!/bin/sh
-
-exec xfce4-session

config/skel/.xsessionrc

@@ -1,16 +0,0 @@
-#!/bin/sh
-
-export XDG_CACHE_HOME="${HOME:?}"/.cache
-export XDG_CONFIG_DIRS=/etc/xdg/xdg-xubuntu:/etc/xdg
-export XDG_CONFIG_HOME="${HOME:?}"/.config
-export XDG_CURRENT_DESKTOP=XFCE
-export XDG_DATA_DIRS=/usr/share/xubuntu:/usr/share/xfce4:/usr/local/share:/usr/share
-export XDG_DATA_HOME="${HOME:?}"/.local/share
-export XDG_MENU_PREFIX=xfce-
-export XDG_RUNTIME_DIR=/run/user/"${UNPRIVILEGED_USER_UID:?}"
-export XDG_SESSION_DESKTOP=xubuntu
-export XDG_SESSION_TYPE=x11
-
-if [ -z "${VGL_DISPLAY-}" ] && [ -n "${DISPLAY-}" ]; then
-	export VGL_DISPLAY="${DISPLAY:?}"
-fi