harness: remove references to unavailable instrumentation
harness: remove references to unavailable instrumentation

 - cover.go was not imported from "testing"
 - "internal/race" is not available to this code
 - mutex profiling is not available in go1.7

dm0-/mantle,marineam/mantle,quantum/coreos-mantle,dm0-/mantle,glevand/coreos--mantle,glevand/coreos--mantle,quantum/coreos-mantle,marineam/mantle