test: new testcase for gccgo bug

Updates #33158.

Change-Id: Id87eb00ddcb104ba8e7a0d2f6cf324a77a84f4a9
Reviewed-on: https://go-review.googlesource.com/c/go/+/186717Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

test/fixedbugs/issue33158.dir/a.go

+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package a
+
+var GS string
+
+func M() string {
+	if s := getname("Fred"); s != "" {
+		return s
+	}
+	if s := getname("Joe"); s != "" {
+		return s
+	}
+
+	return string("Alex")
+}
+
+// getname can be any function returning a string, just has to be non-inlinable.
+
+//go:noinline
+func getname(s string) string {
+	return s + "foo"
+}

test/fixedbugs/issue33158.dir/b.go

+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package b
+
+import "a"
+
+func B() string {
+	return a.M()
+}

test/fixedbugs/issue33158.go

+// compiledir
+
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Issue 33158: gccgo duplicate def error from importing inlinable function
+
+package ignored