debug/dwarf: remove unused field addrsize from Data
debug/dwarf: remove unused field addrsize from Data

The addrsize field is not a constant for an entire executable
file, and is now handled by the dataFormat interface when
reading the data.

R=golang-dev, minux.ma, rsc
CC=golang-dev
https://codereview.appspot.com/41620043

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