Removed flag that would have determined whether the first, or last, element of
a waitlist should be choosen. This will be implemented in a more specific
fashion by a separate waitlist class. 



git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@13408 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c