WiP: fix environs tests on windows

Unfortunately, permission checking on Windows does not work as expected. For example, doing a:

```go
os.Chmod("C:/test.txt", 0600)
```

will set permissions to:

```
-rw-rw-rw-
```
Note that we don't actually specify -compiler=gccgo, so go just uses the default toolchain (whatever built the go tool, I think?)
-gccgoflags should be ignored if the gc compiler is used, so is this actually necessary?