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>