arm/lib: Add XAUTHORITY to runfvp environment

aa89fe3f ensured environment variables necessary for GUI applications
are passed through to the model despite runfvp env var restrictions. Add
XAUTHORITY to this list. This is useful when doing X-forwarding with
Kas, which creates its own home directory.

Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

meta-arm/lib/fvp/runner.py

@@ -91,7 +91,7 @@ class FVPRunner:
         # Pass through environment variables needed for GUI applications, such
         # as xterm, to work.
         env = config['env']
-        for name in ('DISPLAY', 'WAYLAND_DISPLAY'):
+        for name in ('DISPLAY', 'WAYLAND_DISPLAY', 'XAUTHORITY'):
             if name in os.environ:
                 env[name] = os.environ[name]