Noder pass will build a closure to implement generic function
instantiation which may produce `.dict` and `.rcvr` ident.
Since we allow `.dict` during exporting, we should allow `.rcvr` too.
Fixes #52241.
Change-Id: Ifc3912ba5155b5ac1887f20830da64f4fb3fceb6
Reviewed-on: https://go-review.googlesource.com/c/go/+/404314
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com>