snapshot: strip bit from struct cgit_snapshot_format

We had a static bit value in struct cgit_snapshot_format. We do not rely
on it and things can be calculated on the fly. So strip it.

Signed-off-by: Christian Hesse <mail@eworm.de>
diff --git a/ui-shared.c b/ui-shared.c
index 8a786e0..e8c0723 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -1127,7 +1127,7 @@
 
 	prefixlen = filename.len;
 	for (f = cgit_snapshot_formats; f->suffix; f++) {
-		if (!(repo->snapshots & f->bit))
+		if (!(repo->snapshots & cgit_snapshot_format_bit(f)))
 			continue;
 		strbuf_setlen(&filename, prefixlen);
 		strbuf_addstr(&filename, f->suffix);