cmd/pprof: giggabyte

[alicebob]

pprof has this case statement:

case "gb", "gbyte", "giggabyte":

https://github.com/golang/go/blob/master/src/cmd/pprof/internal/report/report.go#L1534

How many bytes go in a gigga?

[bradfitz]

@rsc, are we allowed to modify pprof in our tree, or is there an upstream we should fix first and then pull down?