Fix division in CPU usage calculation on Windows.
Fix division in CPU usage calculation on Windows.

everbase/benchmark,mockingbirdnest/benchmark,efcs/benchmark,eliben/benchmark,codygray/benchmark,disconnect3d/benchmark,xlqian/benchmark,chemhack/benchmark,LepelTsmok/benchmark,nickhutchinson/benchmark,fuchsia-mirror/third_party-benchmark,LepelTsmok/benchmark,eliben/benchmark,LepelTsmok/benchmark,nickhutchinson/benchmark-cxx03,google/benchmark,eliben/benchmark,ntx-/benchmark,disconnect3d/benchmark,codygray/benchmark,disconnect3d/benchmark,xlqian/benchmark,fuchsia-mirror/third_party-benchmark,nickhutchinson/benchmark-cxx03,nickhutchinson/benchmark-cxx03,codygray/benchmark,nickhutchinson/benchmark,eliben/benchmark,efcs/benchmark,ntx-/benchmark,xlqian/benchmark,google/benchmark,chemhack/benchmark,xlqian/benchmark,nickhutchinson/benchmark,everbase/benchmark,efcs/benchmark,disconnect3d/benchmark,nickhutchinson/benchmark,everbase/benchmark,everbase/benchmark,chemhack/benchmark,ntx-/benchmark,nickhutchinson/benchmark-cxx03,mockingbirdnest/benchmark,codygray/benchmark,google/benchmark,efcs/benchmark,mockingbirdnest/benchmark,LepelTsmok/benchmark,mockingbirdnest/benchmark,chemhack/benchmark,ntx-/benchmark,fuchsia-mirror/third_party-benchmark,fuchsia-mirror/third_party-benchmark