lock-free-queue

Based on Hazard Pointers, implemented in C according to Maged M. Michael's paper

Note:

1. You can implement a bounded queue by using queue_attr_t.
2. Tested by Cppcheck, Valgrind, and ThreadSanitizer roughly
3. ./wrapper_test.sh "./main 1000 10 0" 10 means executing "./main 1000 10 0" 10 times

to-do list:

1. Remove retired_next from the struct node. (is it possible?)
2. Implement PrepareForReuse().
3. use of size_t is preferred