add cgo option to Makefile (#2171)
add cgo option to Makefile (#2171)


coredns/coredns,ii/coredns,ii/coredns,jremond/coredns,chrisohaver/coredns,jremond/coredns,yongtang/coredns,miekg/coredns,miekg/coredns,johnbelamaric/coredns,johnbelamaric/coredns