`undefined: syscall.Stat_t` Error on windows7

Hi, @mipearson 
When I run 
```
go get github.com/mipearson/rfw
```
on windows 7 64bit.
it occured:
```
GOPATH\src\github.com\mipearson\rfw\rfw.go:63: undefined: syscall.Stat_t
GOPATH\src\github.com\mipearson\rfw\rfw.go:64: undefined: syscall.Stat
```
-----------------------
OS: windows7 64bit
go version go1.7.3 windows/amd64