midx: mark `get_midx_checksum()` arguments as const

To make clear that the function `get_midx_checksum()` does not do
anything to modify its argument, mark the MIDX pointer as const.

The following commit will rename this function altogether to make clear
that it returns the raw bytes of the checksum, not a hex-encoded copy of
it.

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

1 files changed, 1 insertions, 1 deletions

diff --git a/midx.c b/midx.c
index a75ea99a0d..2a6b18954c 100644
--- a/midx.c
+++ b/midx.c
@@ -24,7 +24,7 @@ void clear_incremental_midx_files_ext(struct odb_source *source, const char *ext
 int cmp_idx_or_pack_name(const char *idx_or_pack_name,
 			 const char *idx_name);
 
-const unsigned char *get_midx_checksum(struct multi_pack_index *m)
+const unsigned char *get_midx_checksum(const struct multi_pack_index *m)
 {
 	return m->data + m->data_len - m->source->odb->repo->hash_algo->rawsz;
 }