Include error to Aron generated class on first build in armarx/skills/navigation

Some people reported an error like this on their first build:

.../code/armarx/skills/navigation/build/source/armarx/navigation/core/aron/Graph.aron.generated.h:38:10: fatal error: RobotAPI/libraries/armem/aron/MemoryID.aron.generated.h: No such file or directory
 #include <RobotAPI/libraries/armem/aron/MemoryID.aron.generated.h>

(Reported by @nicolasschreiber)