cmd/compile: internal compiler error: getinarg: not a func int

gc crashes on the following program:

``` go
package n
func F(interface{int}){}
func s(){F(3)}
```

```
go.go:3: internal compiler error: getinarg: not a func int
```

go version devel +71832ff Fri Jul 3 21:39:04 2015 +0000 linux/amd64
