Add windows support

testdata/scripts/goversion.txt

@@ -1,6 +1,5 @@
-[!exec:sh] skip
+cp go.sh .bin/go
-
+cp go.bat .bin/go.bat
-cp go .bin/go
 chmod 777 .bin/go
 
 # Check incorrect go install
@@ -42,7 +41,11 @@ env GO_VERSION='go version go1.15.2 windows/amd64'
 
 -- main.go --
 package main
--- go --
+-- go.sh --
 #!/bin/sh
 
 [ -z "$GO_VERSION" ] && exit 1 || echo "$GO_VERSION"
+
+-- go.bat --
+@echo off
+IF DEFINED GO_VERSION (echo %GO_VERSION%) ELSE (exit 1)