build: lengthen timeout for the lengthy runtime test         To fix build on (overheated) Linux/ARM builder.
build: lengthen timeout for the lengthy runtime test
        To fix build on (overheated) Linux/ARM builder.

R=golang-dev, dave
CC=golang-dev
http://codereview.appspot.com/5865051

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