Illumos 4914

Illumos 4914 - zfs on-disk bookmark structure should be named *_phys_t
    
4914 zfs on-disk bookmark structure should be named *_phys_t
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com>
Approved by: Robert Mustacchi <rm@joyent.com>
    
Porting notes:
    
    There were a number of zfsonlinux-specific uses of zbookmark_t which
    needed to be updated.  This should reduce the likelihood of further
    problems like issue #2094 from occurring.
    
Ported by: Tim Chase <tim@chase2k.com>