test: split golden.out into expected output per test

This will permit gccgo to check test output.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5554056
diff --git a/test/ken/intervar.go b/test/ken/intervar.go
index c2aaaa8..73d1b06 100644
--- a/test/ken/intervar.go
+++ b/test/ken/intervar.go
@@ -7,7 +7,7 @@
 package main
 
 type	Iputs	interface {
-	puts	(s string);
+	puts	(s string) string;
 }
 
 // ---------
@@ -17,9 +17,9 @@
 	put	Iputs;
 }
 
-func (p *Print) dop() {
-	print(" print ", p.whoami);
-	p.put.puts("abc");
+func (p *Print) dop() string {
+	r := " print " + string(p.whoami + '0')
+	return r + p.put.puts("abc");
 }
 
 // ---------
@@ -29,9 +29,9 @@
 	put	Iputs;
 }
 
-func (b *Bio) puts(s string) {
-	print(" bio ", b.whoami);
-	b.put.puts(s);
+func (b *Bio) puts(s string) string {
+	r := " bio " + string(b.whoami + '0')
+	return r + b.put.puts(s);
 }
 
 // ---------
@@ -41,8 +41,8 @@
 	put	Iputs;
 }
 
-func (f *File) puts(s string) {
-	print(" file ", f.whoami, " -- ", s);
+func (f *File) puts(s string) string {
+	return " file " + string(f.whoami + '0') + " -- " + s
 }
 
 func
@@ -59,6 +59,9 @@
 
 	f.whoami = 3;
 
-	p.dop();
-	print("\n");
+	r := p.dop();
+	expected := " print 1 bio 2 file 3 -- abc"
+	if r != expected {
+		panic(r + " != " + expected)
+	}
 }