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/helloworld.out b/test/helloworld.out
new file mode 100644
index 0000000..4b5fa63
--- /dev/null
+++ b/test/helloworld.out
@@ -0,0 +1 @@
+hello, world