circular priority queue implementation based on linked list
clean- clean all priority queue data
getHead- get priority queue head pointer
getCapacity- get priority queue capacity
travel- travel through all priority queue
insert- user provide custome compare function to tell priority queue how to insert
find- find the given data, return it's position if found else return -1
delete_element- give data, remove the correspond node from circular priority queue
isEmpty- checkout the circular priority queue is empty or not
make unit queuecp
make test queuecp
run the above command at root directory