SMGState does not need to implement Targetable,
it had only an effect if an automaton was used to check for memory
safety problems, in which case it is not necessary
(because the automaton itself then signals that a target state has been
found).

git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@13111 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c