feat: dfm-io build depend compatibility with diff environments.

dfm-io 构建依赖引入'|'(或)关系，允许在不同环境中编译，
当环境中不存在 libdfm-io-dev 时，将不会使用 dfm-io 拷贝优化。
* 引入的 qttools5-private-dev 不会引入其它安装依赖；
* 注意：后续环境或 control 文件变化导致 qttools5-private-dev
  已被安装而不安装 libdfm-io-dev.

Log: dfm-io 构建依赖兼容不同环境
Influence: debian/control
Change-Id: I9a0c5c5c53d101eb34dfec186097eec17a5084ce

debian/control

@@ -36,8 +36,11 @@ Build-Depends:
  libmediainfo-dev,
  libffmpegthumbnailer-dev,
  libtiff-dev,
-# Enable use dfm io to copy MTP mount file.
- libdfm-io-dev
+# Enable use dfm io to copy MTP mount file, Use `|`(or) relationship to 
+# compatible different environments, qttools5-private-dev will not be used.
+# WARNING: control file changes may cause qttools5-private-dev to be installed
+# instead of libdfm-io-dev.
+ libdfm-io-dev | qttools5-private-dev
 Standards-Version: 3.9.8
 Homepage: http://www.deepin.org