runtime: code cleanup about map
1.Revise ambiguous comments: "all current buckets" means buckets in hmap.buckets, actually current bucket and all the overflow buckets connected to it are full
2.All the pointer address add use src/runtime/stubs.go:add, keep the code style uniform
Change-Id: Idc7224dbe6c391e1b03bf5d009c3734bc75187ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/257979
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>