Functions exported on behalf of other packages need to have their
argument stack maps specified explicitly.  They don't get an implicit
map because they are not in the local package, and if they get defer'd
they need argument maps.

Fixes #24419

Change-Id: I35b7d8b4a03d4770ba88699e1007cb3fcb5397a9
Reviewed-on: https://go-review.googlesource.com/122676
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>