cmd/5c: fix dataflag annotation
cmd/5c: fix dataflag annotation

file        old_size     new_size    base@c1ce95068533
bin/go      14717392     6287824     5918236

this huge size difference is due to GC data for runtime.mheap
(NOPTR dataflag is not obeyed).

R=rsc, dave
CC=golang-dev
http://codereview.appspot.com/6547051

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