Only enable vulkan by default on X11

artriculate

@@ -22,6 +22,9 @@ echo "Running cmd: $cmd with args: $args"
 #    export LD_LIBRARY_PATH="$LD_LIBRARY_PATH /opt/libmali-gbm/"
 #fi
 
-export QSG_RHI_BACKEND=vulkan
+# Default to vulkan on X11
+if xhost >& /dev/null ; then
+    export QSG_RHI_BACKEND=vulkan
+fi
 
 QSG_INFO=1 $cmd $args