net: fix typo in lookup_windows getprotobyname

Change-Id: Ia6d40ead1e54dd0b8998370cbabc2d7cd8b7aa0b
Reviewed-on: https://go-review.googlesource.com/18470Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/lookup_windows.go

@@ -19,7 +19,7 @@ var (
 func getprotobyname(name string) (proto int, err error) {
 	p, err := syscall.GetProtoByName(name)
 	if err != nil {
-		return 0, os.NewSyscallError("getorotobyname", err)
+		return 0, os.NewSyscallError("getprotobyname", err)
 	}
 	return int(p.Proto), nil
 }