clean before building a specific arch (#1168)
clean before building a specific arch (#1168)

- make gets tricked by the existence of the binaries, and the build is
   very happy to just copy whatever binary exists at the time. All
   existing non-amd64 builds contain amd64 binaries.
kubernetes-incubator/service-catalog,kubernetes-sigs/service-catalog,jboyd01/service-catalog,martinmaly/service-catalog,pmorie/service-catalog,vaikas-google/service-catalog,kibbles-n-bytes/service-catalog,n3wscott/service-catalog,MHBauer/service-catalog,staebler/service-catalog,jboyd01/service-catalog,jboyd01/service-catalog,kubernetes-incubator/service-catalog,kubernetes-incubator/service-catalog,duglin/service-catalog,duglin/service-catalog,MHBauer/service-catalog,kibbles-n-bytes/service-catalog,MHBauer/service-catalog,kubernetes-sigs/service-catalog,kubernetes-incubator/service-catalog,vaikas-google/service-catalog,n3wscott/service-catalog,staebler/service-catalog,duglin/service-catalog,n3wscott/service-catalog,kubernetes-incubator/service-catalog,kubernetes-sigs/service-catalog,mdshuai/service-catalog,MHBauer/service-catalog,staebler/service-catalog,kubernetes-sigs/service-catalog,vaikas-google/service-catalog,jboyd01/service-catalog,martinmaly/service-catalog,kibbles-n-bytes/service-catalog,kubernetes-sigs/service-catalog,kubernetes-sigs/service-catalog,n3wscott/service-catalog,pmorie/service-catalog,staebler/service-catalog,n3wscott/service-catalog,jboyd01/service-catalog,duglin/service-catalog,kibbles-n-bytes/service-catalog,mdshuai/service-catalog,kibbles-n-bytes/service-catalog,kibbles-n-bytes/service-catalog,duglin/service-catalog,MHBauer/service-catalog,duglin/service-catalog,martinmaly/service-catalog,staebler/service-catalog,MHBauer/service-catalog,krancour/service-catalog,jboyd01/service-catalog,staebler/service-catalog,n3wscott/service-catalog,pmorie/service-catalog,krancour/service-catalog,krancour/service-catalog,kubernetes-incubator/service-catalog,mdshuai/service-catalog