[dev.power64] cmd/9c: add Makefile
[dev.power64] cmd/9c: add Makefile

LGTM=rsc
R=rsc, iant
CC=golang-codereviews
https://codereview.appspot.com/121370043

webfd/go-zh,d0f/go-zh,webfd/go-zh,webfd/go-zh,bryanxu/go-zh,webfd/go-zh,d0f/go-zh,bryanxu/go-zh,bryanxu/go-zh,d0f/go-zh,webfd/go-zh,d0f/go-zh,d0f/go-zh,bryanxu/go-zh,bryanxu/go-zh,bryanxu/go-zh,d0f/go-zh,d0f/go-zh,webfd/go-zh,webfd/go-zh,webfd/go-zh,d0f/go-zh,bryanxu/go-zh,bryanxu/go-zh