[release-branch.go1.17] runtime: don't block preemption signal in new M's or ensureSigM
No test because we already have a test in the syscall package.
The issue reports 1 failure per 100,000 iterations, which is rare enough
that our builders won't catch the problem.
For #52226
Fixes #52374
Change-Id: I17633ff6cf676b6d575356186dce42cdacad0746
Reviewed-on: https://go-review.googlesource.com/c/go/+/400315
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
(cherry picked from commit
e3982660a73b04a87c08215cb5aaa16d816ea573)
Reviewed-on: https://go-review.googlesource.com/c/go/+/400317
Reviewed-by: Austin Clements <austin@google.com>