[qrvthtool] ConfigStore.cpp: #include <cassert>

Needed with gcc-5.4.0 on Ubuntu 16.04, but wasn't needed on my
main Gentoo system with gcc-15.1.0 for some reason.

src/qrvthtool/config/ConfigStore.cpp

@@ -9,7 +9,7 @@
 #include "ConfigStore.hpp"
 #include "git.h"
 
-// Qt includes.
+// Qt includes
 #include <QtCore/QCoreApplication>
 #include <QtCore/QSettings>
 #include <QtCore/QDir>
@@ -23,9 +23,12 @@
 #include <QtCore/QMetaObject>
 #include <QtCore/QMetaMethod>
 
-// Default settings.
+// Default settings
 #include "ConfigDefaults.hpp"
 
+// C includes (C++ namespace)
+#include <cassert>
+
 // C++ STL classes
 #include <map>
 #include <vector>