This routine initializes the condition variable attributes object
    specified by the attr argument with a set of default attribute
    values.

    When an attributes object is used to create a condition
    variable, the values of the individual attributes determine the
    characteristics of the new condition variable. Attributes objects
    act as additional arguments to condition variable creation.
    Changing individual attributes in an attributes object does not
    affect any condition variables that were previously created using
    that attributes object.

    You can use the same condition variable attributes object in
    successive calls to pthread_condattr_init(), from any thread.
    If multiple threads can change attributes in a shared attributes
    object, your program must use a mutex to protect the integrity of
    that attributes object.

    Results are undefined if this routine is called and the attr
    argument specifies a condition variable attributes object that is
    already initialized.

    Currently, on OpenVMS systems, no attributes affecting condition
    variables are defined; you cannot change any attributes in the
    condition variable attributes object. On Tru64 UNIX systems, the
    PSHARED attribute is defined.

    The pthread_condattr_init() and pthread_condattr_destroy()
    routines are provided for future expandability of the pthread
    interface and to conform with the POSIX.1 standard. These
    routines serve no useful function, because there are no pthread_
    condattr_set*() type routines available at this time.