Updating the LF MPMC queue and replacing DirQueue with it

Making the MPMC queue support when producers are consumers at the same
time by adding a variable work, mpmc_push_work() that increments work
and mpmc_task_done() that decrements work, and if work = 0 calls
mpmc_producers_finished() that pushes poinsons to wake up sleeping
threads and make them return NULL

Replacing DirQueue, a queue growable with realloc with the MPMC queue

.gitignore

@@ -4,4 +4,4 @@ file_hasher.rdi
 file_hasher.exe
 file_hashes.txt
 file_list.txt
-temp.c
+temp_code.c