weston-init: Let weston run without pam on distros without pam

When pam is not part of distro, user specific XDG_* environment
variables are not available since PAMName=login is in-effective and as a
result weston can not start because it direly needs XDG_RUNTIME_DIR
defined, therefore launching weston directly in systemd service will not
work, therefore call the helper script weston-start, which is also used
with sysvinit

extend enabling fbdev backend fallback to all qemu machines

Reported-by: Marek Vasut <marex@denx.de>
(From OE-Core rev: ae66cf5e03f04361aad2bd8784fb7d42e0f0bb08)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-graphics/wayland/weston-init/qemux86/weston.ini

@@ -1,2 +0,0 @@
-[core]
-backend=fbdev-backend.so

meta/recipes-graphics/wayland/weston-init/weston@.service

@@ -1,37 +1,15 @@
 [Unit]
-Description=Weston Wayland Compositor (on tty7)
+Description=Weston Wayland Compositor
 RequiresMountsFor=/run
-Conflicts=getty@tty7.service plymouth-quit.service
-After=systemd-user-sessions.service getty@tty7.service plymouth-quit-wait.service
+Conflicts=plymouth-quit.service
+After=systemd-user-sessions.service plymouth-quit-wait.service
 
 [Service]
 User=%i
-PermissionsStartOnly=true
-
-# Log us in via PAM so we get our XDG & co. environment and
-# are treated as logged in so we can use the tty:
 PAMName=login
-
-# Grab tty7
-UtmpIdentifier=tty7
-TTYPath=/dev/tty7
-TTYReset=yes
-TTYVHangup=yes
-TTYVTDisallocate=yes
-
-# stderr to journal so our logging doesn't get thrown into /dev/null
-StandardOutput=tty
-StandardInput=tty
-StandardError=journal
-
 EnvironmentFile=-/etc/default/weston
-
-# Weston does not successfully change VT, nor does systemd place us on
-# the VT it just activated for us. Switch manually:
-ExecStartPre=/usr/bin/chvt 7
-ExecStart=/usr/bin/weston --log=${XDG_RUNTIME_DIR}/weston.log $OPTARGS
-
+StandardError=journal
+PermissionsStartOnly=true
 IgnoreSIGPIPE=no
 
-#[Install]
-#Alias=multi-user.target.wants/weston.service
+ExecStart=/usr/bin/weston-start -v -e -- $OPTARGS