Test if the Pbsfile locator works properly with multiple source directories

Pbsfiles that are not supposed to be loaded contain a single 'die' instruction. The following command will display information about how the Pbsfiles are located. -tda adds the pbsfile to the dependency graph dump.

  pbs -no_warp -dsi -tno all -sd . -sd sd1 -sd sd2 -display_subpbs_search_info -display_all_subpbs_alternatives -cw2 green -sfi -tda -o