gitweb: Restore object-named links in item lists

This restores the redundant links removed earlier. It supersedes my patch
to stick slashes to tree entries.

Sorry about the previous version of the patch, an unrelated snapshot link
addition to tree entries slipped through (and it it didn't even compile);
I've dropped the idea of snapshot links in tree entries in the meantime
anyway.

Signed-off-by: Petr Baudis <redacted>
Signed-off-by: Junio C Hamano <redacted>