cmd/vet: %b is a valid floating-point format. Also add a report about "invalid type" from gotype, if -v is set.
cmd/vet: %b is a valid floating-point format.
Also add a report about "invalid type" from gotype, if -v is set.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/7420045

wesolows/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang,wesolows/golang,firebitsbr/golang-old