Function eval_mm_util

* eval_mm_util - Evaluate the space utilization of the student's package * The idea is to remember the high water mark "hwm" of the heap for * an optimal allocator, i.e., no gaps and no internal fragmentation. * Utilization is the ratio hwm/heapsize, where heapsize is the * size of the heap in bytes after running the student's malloc * package on the trace. Note that our implemen