ui-shared: pass separator in to cgit_print_snapshot_links()

cgit_print_snapshot_links() is almost identical to
print_tag_downloads(), so let's extract the difference to a parameter in
preparation for removing print_tag_downloads() in the next commit.

Signed-off-by: John Keeping <john@keeping.me.uk>
Reviewed-by: Christian Hesse <mail@eworm.de>

ui-commit.c

@@ -110,7 +110,7 @@ void cgit_print_commit(char *hex, const char *prefix)
 	}
 	if (ctx.repo->snapshots) {
 		html("<tr><th>download</th><td colspan='2' class='sha1'>");
-		cgit_print_snapshot_links(ctx.repo, hex);
+		cgit_print_snapshot_links(ctx.repo, hex, "<br/>");
 		html("</td></tr>");
 	}
 	html("</table>\n");