runtime: report GCSys and OtherSys in heap profile

The comment block at the end of the heap profile includes *almost*
everything from MemStats. Add the missing fields. These are useful for
debugging RSS that has gone to GC-internal data structures.

Change-Id: I0ee8a918d49629e28fd8fd2bf6861c4529461c24
Reviewed-on: https://go-review.googlesource.com/29276
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>

src/runtime/pprof/pprof.go

@@ -540,6 +540,8 @@ func writeHeap(w io.Writer, debug int) error {
 	fmt.Fprintf(w, "# MSpan = %d / %d\n", s.MSpanInuse, s.MSpanSys)
 	fmt.Fprintf(w, "# MCache = %d / %d\n", s.MCacheInuse, s.MCacheSys)
 	fmt.Fprintf(w, "# BuckHashSys = %d\n", s.BuckHashSys)
+	fmt.Fprintf(w, "# GCSys = %d\n", s.GCSys)
+	fmt.Fprintf(w, "# OtherSys = %d\n", s.OtherSys)
 
 	fmt.Fprintf(w, "# NextGC = %d\n", s.NextGC)
 	fmt.Fprintf(w, "# PauseNs = %d\n", s.PauseNs)