Move linux-only variable into linux/cygwin block
Move linux-only variable into linux/cygwin block

eliben/benchmark,fuchsia-mirror/third_party-benchmark,google/benchmark,fuchsia-mirror/third_party-benchmark,chandlerc/benchmark,chemhack/benchmark,LepelTsmok/benchmark,mockingbirdnest/benchmark,codygray/benchmark,xlqian/benchmark,xlqian/benchmark,codygray/benchmark,everbase/benchmark,disconnect3d/benchmark,subailong/benchmark,ntx-/benchmark,fuchsia-mirror/third_party-benchmark,Photonomie/benchmark,subailong/benchmark,disconnect3d/benchmark,codygray/benchmark,gezidan/benchmark,eliben/benchmark,chandlerc/benchmark,subailong/benchmark,bowlofstew/benchmark,nickhutchinson/benchmark-cxx03,LepelTsmok/benchmark,gezidan/benchmark,LepelTsmok/benchmark,dcoeurjo/benchmark,bowlofstew/benchmark,gezidan/benchmark,nickhutchinson/benchmark,xlqian/benchmark,efcs/benchmark,mockingbirdnest/benchmark,chemhack/benchmark,nickhutchinson/benchmark-cxx03,google/benchmark,eliben/benchmark,gezidan/benchmark,ntx-/benchmark,everbase/benchmark,nickhutchinson/benchmark,ntx-/benchmark,everbase/benchmark,quantumsteve/benchmark,nickhutchinson/benchmark-cxx03,quantumsteve/benchmark,Photonomie/benchmark,disconnect3d/benchmark,efcs/benchmark,chandlerc/benchmark,codygray/benchmark,nickhutchinson/benchmark-cxx03,quantumsteve/benchmark,bowlofstew/benchmark,Photonomie/benchmark,nickhutchinson/benchmark,dcoeurjo/benchmark,efcs/benchmark,everbase/benchmark,subailong/benchmark,dcoeurjo/benchmark,fuchsia-mirror/third_party-benchmark,disconnect3d/benchmark,nickhutchinson/benchmark,chemhack/benchmark,mockingbirdnest/benchmark,LepelTsmok/benchmark,chemhack/benchmark,eliben/benchmark,google/benchmark,quantumsteve/benchmark,efcs/benchmark,Photonomie/benchmark,chandlerc/benchmark,ntx-/benchmark,bowlofstew/benchmark,mockingbirdnest/benchmark,xlqian/benchmark