fix golint warnings/errors on pkg/system and pkg/stdcopy

Signed-off-by: Zhang Wei <zhangwei555@huawei.com>

system/lstat_windows.go

@@ -6,21 +6,17 @@ import (
 	"os"
 )
 
-// Some explanation for my own sanity, and hopefully maintainers in the
-// future.
-//
 // Lstat calls os.Lstat to get a fileinfo interface back.
 // This is then copied into our own locally defined structure.
 // Note the Linux version uses fromStatT to do the copy back,
 // but that not strictly necessary when already in an OS specific module.
-
-func Lstat(path string) (*Stat_t, error) {
+func Lstat(path string) (*StatT, error) {
 	fi, err := os.Lstat(path)
 	if err != nil {
 		return nil, err
 	}
 
-	return &Stat_t{
+	return &StatT{
 		name:    fi.Name(),
 		size:    fi.Size(),
 		mode:    fi.Mode(),