Create pkg/system and move stuff there from archive

This is a package for generic system calls etc that for some reason
is not yet supported by "syscall", or where it is different enough
for the different ports to need portability wrappers.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)

system/utimes_linux.go

@@ -0,0 +1,31 @@
+package system
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+func LUtimesNano(path string, ts []syscall.Timespec) error {
+	// These are not currently available in syscall
+	AT_FDCWD := -100
+	AT_SYMLINK_NOFOLLOW := 0x100
+
+	var _path *byte
+	_path, err := syscall.BytePtrFromString(path)
+	if err != nil {
+		return err
+	}
+
+	if _, _, err := syscall.Syscall6(syscall.SYS_UTIMENSAT, uintptr(AT_FDCWD), uintptr(unsafe.Pointer(_path)), uintptr(unsafe.Pointer(&ts[0])), uintptr(AT_SYMLINK_NOFOLLOW), 0, 0); err != 0 && err != syscall.ENOSYS {
+		return err
+	}
+
+	return nil
+}
+
+func UtimesNano(path string, ts []syscall.Timespec) error {
+	if err := syscall.UtimesNano(path, ts); err != nil {
+		return err
+	}
+	return nil
+}