cmd/gc: be more tolerant with recursive types when checking map types.
A nested TFORW type would push algtype1 into an impossible case.
Fixes #5125.
R=golang-dev, daniel.morsing
CC=golang-dev
https://golang.org/cl/8213043
diff --git a/test/fixedbugs/issue5125.go b/test/fixedbugs/issue5125.go
new file mode 100644
index 0000000..c049df3
--- /dev/null
+++ b/test/fixedbugs/issue5125.go
@@ -0,0 +1,10 @@
+// compiledir
+
+// Copyright 2013 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 5125: cyclic dependencies between types confuse
+// the hashability test during import.
+
+package ignored
