qemu_v8: xen: add domu helper script

Adds a helper script to create a Xen DomU from a Dom0 root shell.

Signed-off-by: Jerome Forissier <jerome@forissier.org>
Reviewed-by: Ruchika Gupta <ruchika.gupta@linaro.org>

br-ext/board/qemu/overlay/bin/domu

+#!/bin/sh
+
+# Helper script to create Xen DomU and switch to it.
+# To be used on QEMUv8 from a Dom0 root shell. For example:
+#
+#   optee_qemu_v8/build $ make -j10 XEN_BOOT=y run
+#   ...
+#   Welcome to Buildroot, type root or test to login
+#   buildroot login: root
+#   # domu
+#   ...
+#   Welcome to Buildroot, type root or test to login
+#   buildroot login: test
+#   $ xtest
+#   ...
+
+if [ $(id -u) -ne 0 ]; then
+  echo $0: please run as root.
+  exit 1
+fi
+
+set -e
+set -v
+cd /mnt/host/build/qemu_v8/xen
+xl create guest.cfg
+xl console domu