Do not include current path in the "tree" menu link

When generating the menu links on repo pages the tree link included the
current path. This made the link pretty useless whenever the current path
was set so this commit just passes NULL instead.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

ui-shared.c

@@ -305,7 +305,7 @@ void cgit_print_pageheader(char *title, int show_search)
 			      cgit_query_sha1, cgit_query_path);
 		html(" ");
 		cgit_tree_link("tree", NULL, NULL, cgit_query_head,
-			       cgit_query_sha1, cgit_query_path);
+			       cgit_query_sha1, NULL);
 		html(" ");
 		cgit_commit_link("commit", NULL, NULL, cgit_query_head,
 			      cgit_query_sha1);