Fix cross compile with syscall

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)

namespaces/sync_pipe.go

@@ -17,20 +17,6 @@ type SyncPipe struct {
 	parent, child *os.File
 }
 
-func NewSyncPipe() (s *SyncPipe, err error) {
-	s = &SyncPipe{}
-
-	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM|syscall.SOCK_CLOEXEC, 0)
-	if err != nil {
-		return nil, err
-	}
-
-	s.child = os.NewFile(uintptr(fds[0]), "child syncpipe")
-	s.parent = os.NewFile(uintptr(fds[1]), "parent syncpipe")
-
-	return s, nil
-}
-
 func NewSyncPipeFromFd(parendFd, childFd uintptr) (*SyncPipe, error) {
 	s := &SyncPipe{}
 

namespaces/sync_pipe_linux.go

@@ -0,0 +1,20 @@
+package namespaces
+
+import (
+	"os"
+	"syscall"
+)
+
+func NewSyncPipe() (s *SyncPipe, err error) {
+	s = &SyncPipe{}
+
+	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM|syscall.SOCK_CLOEXEC, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	s.child = os.NewFile(uintptr(fds[0]), "child syncpipe")
+	s.parent = os.NewFile(uintptr(fds[1]), "parent syncpipe")
+
+	return s, nil
+}