statd: Use the new nsm_ file.c calls in sm_notify

Replace open-coded accesses to on-disk NSM data with calls to the new
libnsm.a API.

One major change is that sync(2) is no longer called when the NSM
state number is updated at boot time.  Otherwise sm-notify should
behave much the same as it did before.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>