linux complie fix

[Wolftronics-SBC]

`difu /example/addons.make b/example/addons.make
--- a/example/addons.make 2016-05-27 14:30:02.000000000 +0000
+++ b/example/addons.make 2016-05-27 14:16:07.000000000 +0000
@@ -2,3 +2,5 @@

These are the names of the folders in OF_ROOT/addons

ofxOpenCv
+ofxControlPanel
+ofxXmlSettings
\ No newline at end of file
`