cmd/objdump: rewrite in Go
Update cmd/dist not to build the C version.
Update cmd/go to install the Go version to the tool directory.
Update #7452
This is the basic logic needed for objdump, and it works well enough
to support the pprof list and weblist commands. A real disassembler
needs to be added in order to support the pprof disasm command
and the per-line assembly displays in weblist. That's still to come.
Probably objdump will move to go.tools when the disassembler
is added, but it can stay here for now.
LGTM=minux.ma
R=golang-codereviews, minux.ma
CC=golang-codereviews, iant, r
https://golang.org/cl/
87580043