change `mount.rs` find_parent_mount from pub to private

[rongfu.leng]

The current find_parent_mount method is only in impl Mount use, we can change to private fn from pub fn.

youki/crates/libcontainer/src/rootfs/mount.rs

Line 614 in 4d4ce7c

 pub fn find_parent_mount( 

[Yashodhan]

Note that this change would likely be a breaking change, so PR should be labeled accordingly, along with changelog info.

[Toru Komatsu]

@Mossaka Do you use this function in runwasi?

[Jiaxiao Zhou]

No, it's not used in runwasi. However, I would be more careful in making breaking changes if we don't have a strong motivation.

[rongfu.leng]

Thanks every body suggestion, we can hold this issue, keep watch, and then decide how to resolve.