cmd/6l: fix printing of frame size in TEXT instruction
cmd/6l: fix printing of frame size in TEXT instruction

R=ken2
CC=golang-dev
https://codereview.appspot.com/12827043

apparentlymart/golang,pombredanne/go-deleteme,tv42/old-go,apparentlymart/golang,apparentlymart/golang,pombredanne/go-deleteme,tv42/old-go,apparentlymart/golang,pombredanne/go-deleteme,apparentlymart/golang,tv42/old-go,tv42/old-go,pombredanne/go-deleteme,tv42/old-go,apparentlymart/golang,tv42/old-go,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,pombredanne/go-deleteme,pombredanne/go-deleteme