Valgrind Massif result when linking godoc:
On amd64:
                    old          new         -/+
mem_heap_B       185844612    175358047    -5.7%
mem_heap_extra_B    773404       773137    -0.0%

On 386/ARM:
                    old          new         -/+
mem_heap_B       141775701    131289941    -7.4%
mem_heap_extra_B    737011       736955    -0.0%

R=golang-dev, r, dave
CC=golang-dev
https://golang.org/cl/6655045