fix redefintion of qsort_cmpf on RHEL5
fix redefintion of qsort_cmpf on RHEL5

ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz,ellson/graphviz