Temporarily disable 10/01/00[45].cf on OS X

safe_open() changes introduced recently cause this regression:
if user is not a root and does not have rights to the file,
it cannot open it. safe_chmod function first opens the file
and then fchmod()s, so it fails.

OTOH, it is only manifested for non-root for weird file mode
(file owned by user, but user does not have read, write or execute
permission for it), so this is OK to leave it as is for now.
Merge pull request #1155 from dottedmag/tests/safe-open-os-x

Temporarily disable 10/01/00[45].cf on OS X
Queue implementation

This is a simple FIFO implementation using reference counting and
copy on write.

It implements the basic queue operations:
- Head: Return a pointer to the first element without dequeuing it.
- Enqueue: Adds one element to the end of the queue.
- Dequeue: Dequeues the first element of the queue and returns a
pointer to it.

In addition, it implements the basic administrative functions:
- New
- Destroy
- Copy