doc/progs: use test/run.go for testing on Windows
        cgo[1-4].go, go1.go couldn't be tested now
(cgo[1-4].go can only be tested when cgo is enabled, go1.go
contain a list of filenames in the current directory)

R=golang-dev, alex.brainman, rsc
CC=golang-dev
https://golang.org/cl/6218048
diff --git a/doc/progs/interface2.out b/doc/progs/interface2.out
new file mode 100644
index 0000000..085bd01
--- /dev/null
+++ b/doc/progs/interface2.out
@@ -0,0 +1 @@
+type: float64