net: remove duplicate import of runtime

R=rsc
CC=golang-dev
https://golang.org/cl/3999046
diff --git a/src/pkg/net/fd_windows.go b/src/pkg/net/fd_windows.go
index f3e5761..9b91eb3 100644
--- a/src/pkg/net/fd_windows.go
+++ b/src/pkg/net/fd_windows.go
@@ -11,7 +11,6 @@
 	"syscall"
 	"time"
 	"unsafe"
-	"runtime"
 )
 
 // IO completion result parameters.