mdns: fix QA warning of host uid contamination
mdns: fix QA warning of host uid contamination

Fix the following waring by replacing "cp" with "install" since it
can handle the uid and gid correctly.
  WARNING: QA Issue: mdns: /mdns/usr/local/go/src/github.com/hashicorp/mdns/zone_test.go is owned by uid 16568, which is the same as the user running bitbake. This may be due to host contamination [host-user-contaminated]

Signed-off-by: Kevin Hao <f8e4399761033fa055eb299c6d786108bfad24a3@windriver.com>
Signed-off-by: Bruce Ashfield <284cc737d174a260eec2a2a6324a304f84b1ae0f@windriver.com>

OverC/meta-overc,OverC/meta-overc,masselstine/meta-overc,jwessel/meta-overc,OverC/meta-overc,mufeng/meta-overc,masselstine/meta-overc,mufeng/meta-overc,WindRiver-OpenSourceLabs/meta-overc,OverC/meta-overc,masselstine/meta-overc,OverC/meta-overc,WindRiver-OpenSourceLabs/meta-overc,jwessel/meta-overc,WindRiver-OpenSourceLabs/meta-overc,masselstine/meta-overc,mufeng/meta-overc,OverC/meta-overc,jwessel/meta-overc