runtime/pprof: fix profile parser in test
runtime/pprof: fix profile parser in test

Fixes issue 6417.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/13843043

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