- Fixes a catstrophic bug introduced in the merge, wherein liblustre OBD_ALLOC

  wasn't zeroing memory
- eliminate CDEBUG helper dupes; everything references CDEBUG now
- I wanted to keep obd_memory, portals_debug, et al in liblustre, but I can't
  have those bits compiled into userspace utils.  Hence the LUSTRE_UTILS
  preprocessor definition to distinguish them.