Remove windows files

Windows is not going to use containerd because there is already a
similar implementation on windows.  This removes all the windows files
because there is no reason to keep this overhead when its not going to
be used.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

runtime/process_windows.go

@@ -1,29 +0,0 @@
-package runtime
-
-import "os"
-
-// TODO Windows: Linux uses syscalls which don't map to Windows. Needs alternate mechanism
-func getExitPipe(path string) (*os.File, error) {
-	return nil, nil
-}
-
-// TODO Windows: Linux uses syscalls which don't map to Windows. Needs alternate mechanism
-func getControlPipe(path string) (*os.File, error) {
-	return nil, nil
-}
-
-// TODO Windows. Windows does not support signals. Need alternate mechanism
-// Signal sends the provided signal to the process
-func (p *process) Signal(s os.Signal) error {
-	return nil
-}
-
-func populateProcessStateForEncoding(config *processConfig, uid int, gid int) ProcessState {
-	return ProcessState{
-		ProcessSpec: config.processSpec,
-		Exec:        config.exec,
-		Stdin:       config.stdio.Stdin,
-		Stdout:      config.stdio.Stdout,
-		Stderr:      config.stdio.Stderr,
-	}
-}

runtime/runtime_windows.go

@@ -1,10 +0,0 @@
-package runtime
-
-// Checkpoint is not supported on Windows.
-// TODO Windows: Can eventually be factored out entirely.
-type Checkpoint struct {
-}
-
-// PlatformProcessState container platform-specific fields in the ProcessState structure
-type PlatformProcessState struct {
-}