cmd/compile: allow more args in StructMake folding rule
imakeOfStructMake does the right thing, but we never call it
when the StructMake has more than one argument.
Fixes #74908
Change-Id: Ib4b1a025bfb1fa69a325207e47b74bd6217092bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/693615
Auto-Submit: Keith Randall <khr@golang.org> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>