Add a configuration header

backend/config.h.in

@@ -0,0 +1,9 @@
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#define G_LOG_DOMAIN "Katja"
+#define LOCALSTATEDIR "@CMAKE_INSTALL_LOCALSTATEDIR@"
+#define LIBDIR "@CMAKE_INSTALL_LIBDIR@"
+#define SYSCONFDIR "@CMAKE_INSTALL_SYSCONFDIR@"
+
+#endif // CONFIG_H