Revert "runtime: use explicit NOFRAME on darwin/amd64"

Revert "runtime: use explicit NOFRAME on darwin/amd64"

This reverts CL 460235.

Reason for revert: This breaks darwin 10 and 11

Change-Id: I3c663ebe3b77eba45a006a3ebec5cabe667faa9e
Reviewed-on: https://go-review.googlesource.com/c/go/+/463635
Auto-Submit: Quim Muntal <quimmuntal@gmail.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>