Fix missing GL symbols on ARM

Fix taken from https://github.com/projectM-visualizer/projectm/issues/356

---
 src/projectM-qt/qprojectmwidget.hpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/projectM-qt/qprojectmwidget.hpp b/src/projectM-qt/qprojectmwidget.hpp
index f51e2cf..7e03820 100644
--- a/src/projectM-qt/qprojectmwidget.hpp
+++ b/src/projectM-qt/qprojectmwidget.hpp
@@ -22,6 +22,7 @@
 #ifndef QPROJECTM_WIDGET_HPP
 #define QPROJECTM_WIDGET_HPP
 
+#include <GL/gl.h>
 #include <iostream>
 #include "qprojectm.hpp"
 #include <QGLWidget>
-- 
2.32.0