pack-bitmap: tag bitmapped packs with their corresponding MIDX

The next commit will need to use the bitmap's MIDX (if one exists) to
translate bit positions into pack-relative positions in the source pack.

Ordinarily, we'd use the "midx" field of the bitmap_index struct. But
since that struct is defined within pack-bitmap.c, and our caller is in
a separate compilation unit, we do not have access to the MIDX field.

Instead, add a "from_midx" field to the bitmapped_pack structure so that
we can use that piece of data from outside of pack-bitmap.c. The caller
that uses this new piece of information will be added in the following
commit.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/pack-bitmap.h b/pack-bitmap.h
index ff0fd815b8..d7f4b8b8e9 100644
--- a/pack-bitmap.h
+++ b/pack-bitmap.h
@@ -60,6 +60,7 @@ struct bitmapped_pack {
 	uint32_t bitmap_pos;
 	uint32_t bitmap_nr;
 
+	struct multi_pack_index *from_midx; /* MIDX only */
 	uint32_t pack_int_id; /* MIDX only */
 };