misc/emacs: use built-in buffer-base-buffer instead of own variable
misc/emacs: use built-in buffer-base-buffer instead of own variable

R=adonovan
CC=golang-dev
https://codereview.appspot.com/13476043

Committer: Alan Donovan <7069e9552f9d110b0a0f326b96f22f63fb99dfc1@google.com>

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang