NAME
        CreateDir -- Create a new directory

    SYNOPSIS
        lock = CreateDir( name )
        D0                D1

        bptr createdir(strptr)

    FUNCTION
        CreateDir creates a new directory with the specified name. An error
        is returned if it fails.  Directories can only be created on
        devices which support them, e.g. disks.  CreateDir returns an
        exclusive lock on the new directory if it succeeds.

    INPUTS
        name - pointer to a null-terminated string

    RESULTS
        lock - BCPL pointer to a lock or NULL for failure.

    SEE ALSO
        lock(), unlock()