Fix for different GOARCHs

[CalebQ42]

I was having an issue with probonopd/go-appimage not building via TravisCI, particularly with GOARCH=386.

[otiai10]

Thanks a lot.
Can I see exact error message you had?

[CalebQ42]

We were getting this on all TravisCI checks when it got to building it for 386 and arm6.

github.com/otiai10/copy
# github.com/otiai10/copy
github.com/otiai10/copy/stat_times.go:17:29: cannot use stat.Atim.Sec (type int32) as type int64 in argument to time.Unix
github.com/otiai10/copy/stat_times.go:17:44: cannot use stat.Atim.Nsec (type int32) as type int64 in argument to time.Unix
github.com/otiai10/copy/stat_times.go:18:29: cannot use stat.Ctim.Sec (type int32) as type int64 in argument to time.Unix
github.com/otiai10/copy/stat_times.go:18:44: cannot use stat.Ctim.Nsec (type int32) as type int64 in argument to time.Unix

[otiai10]

Shipped as v1.4.1, 👍
Thank you!