rbd: add reference counting to rbd_spec
rbd: add reference counting to rbd_spec

With layered images we'll share rbd_spec structures, so add a
reference count to it.  It neatens up some code also.

A silly get/put pair is added to the alloc routine just to avoid
"defined but not used" warnings.  It will go away soon.

Signed-off-by: Alex Elder <f429030cf5c0faf36fac3d102073b6e63a647baa@inktank.com>
Reviewed-by: Josh Durgin <51652c783f70f5b272ebd02f1fd20d3af7a2449f@inktank.com>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs