The default case in x_cgo_getstackbound does not actually get the stack bound of
the current thread, but estimates the bound based on the default stack size. Add
a comment noting this.
Change-Id: I7d886461f0bbc795834bed37b554417cf3837a2d
Reviewed-on: https://go-review.googlesource.com/c/go/+/563376
Auto-Submit: Michael Pratt <mpratt@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>