Fix various bugs in mca_base_pvar.

Fixes:

 - Segmentation fault when using watermark variables.

 - Segmentation fault when using a handle bound to a no longer valid
   performance variable.

 - Incorrect return codes from MPI_T_pvar_* functions.

cmr=v1.7.4:reviewer=jsquyres
usnic: refactor usnic_stats_callback

Pull the bulk of the functionality out into a new routine,
ompi_btl_usnic_print_stats, which can be used in other debugging
contexts.  This also lets us eliminate the module->final_stats state
tracking.

Reviewed-by: Jeff Squyres <jsquyres@cisco.com>
usnic: add ompi_btl_usnic_component_debug helper

This new routine can be called in exceptional situations, either
conditionally in BTL code or from a debugger, to help with debugging in
cases where MSGDEBUG1/2 or stats logging are impractical but more detail
is needed.

Reviewed-by: Jeff Squyres <jsquyres@cisco.com>
usnic: fix several memory leaks

- some free lists simply were not being OBJ_DESTRUCTed, so they never
  freed their internal memory

- channel->recv_segs.ctx was being assigned in a way that got clobbered
  by ompi_free_list_init_new, so the cleanup code that relied on it
  being set never ran

- numerous other ".ctx" assignments were similarly ineffectual and were
  not being consumed, so I deleted them

Reviewed-by: Jeff Squyres <jsquyres@cisco.com>
usnic: correctly clean up verbs resources

Due to deallocation ordering (and an entirely missed deallocation), we
were leaking modest amounts of memory inside libusnic_verbs.

Reviewed-by: Jeff Squyres <jsquyres@cisco.com>
rcache/vma: fix module finalization memory leaks

Reviewed-by: Jeff Squyres <jsquyres@cisco.com>
mpool/rdma: fix memory leak at module finalize

Reviewed-by: Jeff Squyres <jsquyres@cisco.com>
opal: support __attribute__((__noinline__))

First cut does not attempt any "cross-check".  As we discover compilers
which complain about __noinline__, we will add specific cross checks to
handle those cases.

Reviewed-by: Jeff Squyres <jsquyres@cisco.com>
Fix coprocessor detection by always adding the local daemon's co-processors
to the hash table.

Tested and working on a system with 2 Xeon Phi co-processors.

cmr=v1.7.4:ticket=3847:reviewer=ompi-rm1.7
Add support for the Intel scif interface.

Depends on #3847.

cmr=v1.7.4:reviewer=rhc