MB-8723: Bring back support for DTrace probes

Change-Id: I239b25ca9182289fb7540878d2d08c2e25cc133e
Reviewed-on: http://review.couchbase.org/36073
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>