[analysis-scripts] fix problems in heuristics cg + recursion; improve debug

share/analysis-scripts/build_callgraph.py

share/analysis-scripts/estimate_difficulty.py

share/analysis-scripts/function_finder.py

share/analysis-scripts/heuristic_list_functions.py

tests/fc_script/list_functions.i

tests/fc_script/oracle/heuristic_list_functions.err

tests/fc_script/oracle/heuristic_list_functions.res

tests/fc_script/oracle/recursions.res

tests/fc_script/recursions.i