compiler, runtime: better stack trace for `go f()` where f is nil

The test for this is TestGoNil in the runtime package, which we don't
run yet but will run with a subsequent gotools patch.

Updates golang/go#8045

Change-Id: I930224cd1a7800e6cbc3d13bd75bb9cb840b4b55
Reviewed-on: https://go-review.googlesource.com/46392
Reviewed-by: Than McIntosh <thanm@google.com>
3 files changed