Beautifier: Compile fix on Linux

Change-Id: I335e4e0304b3f57eec8e8a85222a900e20ed70ce
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/beautifier/beautifierplugin.cpp

@@ -53,6 +53,7 @@
 #include <utils/fileutils.h>
 
 #include <QAction>
+#include <QDir>
 #include <QFileInfo>
 #include <QPlainTextEdit>
 #include <QProcess>