Set up basic tracepoints for debugging client id creation/destruction
and session creation/destruction.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Add tracepoints for lookup, lookup_revalidate and atomic_open
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Add tracepoints for inode attribute updates, attribute revalidation,
writeback start/end fsync start/end, attribute change start/end,
permission check start/end.

The intention is to enable performance tracing using 'perf'as well as
improving debugging.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>