compiler: set varargs lowered for imported call expressions

Fix compiler buglet: varargs lowering happens before inlinable
function bodies are written out to export data, so set the "varargs
lowered" flag on call expressions that we import.

Fixes golang/go#32922

Change-Id: Ib2d5a13dcfefd73a6c793a0d9255499c4720b46e
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/184919
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
1 file changed