runtime: replace all callback uses of gentraceback with unwinder

This is a really nice simplification for all of these call sites.

It also achieves a nice performance improvement for stack copying:

goos: linux
goarch: amd64
pkg: runtime
cpu: Intel(R) Xeon(R) CPU E5-2690 v3 @ 2.60GHz
                       │   before    │                after                │
                       │   sec/op    │   sec/op     vs base                │
StackCopyPtr-48          89.25m ± 1%   79.78m ± 1%  -10.62% (p=0.000 n=20)
StackCopy-48             83.48m ± 2%   71.88m ± 1%  -13.90% (p=0.000 n=20)
StackCopyNoCache-48      2.504m ± 2%   2.195m ± 1%  -12.32% (p=0.000 n=20)
StackCopyWithStkobj-48   21.66m ± 1%   21.02m ± 2%   -2.95% (p=0.000 n=20)
geomean                  25.21m        22.68m       -10.04%

Updates #54466.

Change-Id: I31715b7b6efd65726940041d3052bb1c0a1186f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/468297
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>

0 files changed, 0 insertions, 0 deletions