Support long symbolic/hard link path name by reading the linkpath PAX extension

[nullpo-head]

Fix a problem where tar-rs crashes if a symbolic link or hard link in a pax-format archive refers to a path that was longer than 99 characters.

For a new test case, I've updated the pax2.tar so that it includes a symbolic link and a hard link.
Before:

1. aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/

After

1. aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/
2. aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/ccccccccccccccc
3. aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/bbbbbbbbbbbbbbb
4. bbbbbbbbbbbbbbb -> aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/bbbbbbbbbbbbbbb
5. ccccccccccccccc link to aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/aaaaaaaaaaaaaaa/ccccccccccccccc

[alexcrichton]

Thanks!

[frederikbosch]

Does this fix #221?