Revert "runtime: avoid multiple records with identical stacks from MutexProfile"
This reverts CL 595966.
Reason for revert: This CL contains a bug. See the comment in https://go-review.googlesource.com/c/go/+/595966/8#message-
57f4c1f9570b5fe912e06f4ae3b52817962533c0
Change-Id: I48030907ded173ae20a8965bf1b41a713dd06059
Reviewed-on: https://go-review.googlesource.com/c/go/+/598219
Reviewed-by: Than McIntosh <thanm@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>