syscall: update zfiles for linux 386+amd64 (only fmt changes)
syscall: windows: update zfile-generation, regenerate zfiles
add IsTerminal for linux and windows
The linux implementation is based on the one that
can be found in file util.go of Go package go.crypto/ssh/terminal.
I added the Windows version, which didn't exist in that package.
syscall: remove GetUserName, now similarly provided by os/user
examples/registry: add build constraint