Fix instrumentation of object files for dtrace

Change-Id: I0e639d0c1dd88078cc827dd77bcc3d27ac34b74c
Reviewed-on: http://review.couchbase.org/24266
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>