RtlCopyMemory does not work in GOARCH=386

You can use memcpy via msvcrt.dll instead which works on amd64 and 386.

```golang
msvcrt := windows.NewLazyDLL("msvcrt")
memcpy := msvcrt.NewProc("memcpy")
```

This probably also applies to [ExecuteShellcodeSelf ](https://github.com/Ne0nd0g/merlin/blob/1b0ce52d71da62da21cc8f90b97191308e6fe7a9/pkg/agent/exec_windows.go#L106) in Merlin.