Hacky fix for bwrap execution inside the Debian container running under the NVIDIA Docker runtime

Ref: https://github.com/flatpak/flatpak/wiki/User-namespace-requirements

overlay/etc/cont-init.d/80-configure_flatpak.sh

@@ -0,0 +1,13 @@
+
+echo "**** Configure Flatpak ****"
+
+if [ "X${NVIDIA_VISIBLE_DEVICES:-}" != "X" ]; then
+    # Fix some flatpak quirks (not sure what is happening here) for NVIDIA containers
+    mount -t proc none /proc
+    flatpak list
+    echo "Flatpak configured for running inside a Docker container"
+else
+    echo "Flatpak already configured for running inside a Docker container"
+fi
+
+echo "DONE"