Each atomic_base objects holds onto work space in order to
avoid repeated memory allocation calls and thereby increase speed
(until it is deleted).
If an the atomic_base object is global or static because,
the it does not get deleted.
This is a problem when using
to check that all allocated memory has been freed.
Calling this clear function will free all the
memory currently being held onto by the
If there is future use of an atomic_base object,
after a call to clear,
the work space will be reallocated and held onto.
This routine cannot be called
while in parallel
Input File: cppad/core/atomic_base.hpp