[Flatpak] Make alarm-notify use the D-Bus services prefix, if specified

Without it the process cannot own the D-Bus name, thus it doesn't start.

src/services/evolution-alarm-notify/e-alarm-notify.c

@@ -34,7 +34,11 @@
 
 #include "e-alarm-notify.h"
 
+#ifdef DBUS_SERVICES_PREFIX
+#define APPLICATION_ID DBUS_SERVICES_PREFIX "." "org.gnome.Evolution-alarm-notify"
+#else
 #define APPLICATION_ID "org.gnome.Evolution-alarm-notify"
+#endif
 
 struct _EAlarmNotifyPrivate {
 	ESourceRegistry *registry;