Remove the unneeded build tag from the config_linux.go
Remove the unneeded build tag from the config_linux.go

config_linux.go already has the "_linux" for the go build,
so the build tag in the file is redundant.

Signed-off-by: Lai Jiangshan <b337eedf453972390e4695e362aeea2634ef4e0c@gmail.com>

ChengTiesheng/specs,runcom/specs,ujuc/specs,hqhq/runtime-spec,opencontainers/runtime-spec,hqhq/specs,vbatts/specs,gao-feng/specs,mheon/specs,wking/opencontainer-specs,cloudfoundry-incubator/specs,wangkirin/specs,marcosnils/specs,jonboulle/specs,HardikDR/specs,zenlinTechnofreak/specs,wking/opencontainer-runtime-spec,laijs/specs,opencontainers/specs