UI: Use icons from theme on Linux

UI/window-basic-stats.cpp

@@ -139,7 +139,8 @@ OBSBasicStats::OBSBasicStats(QWidget *parent, bool closeable)
 	resize(800, 280);
 
 	setWindowTitle(QTStr("Basic.Stats"));
-	setWindowIcon(QIcon(":/res/images/obs.png"));
+	setWindowIcon(QIcon::fromTheme("obs", QIcon(":/res/images/obs.png")));
+
 	setWindowModality(Qt::NonModal);
 	setAttribute(Qt::WA_DeleteOnClose, true);