commit-graph: anonymize data in chunk_write_fn

In preparation for creating an API around file formats using chunks and
tables of contents, prepare the commit-graph write code to use
prototypes that will match this new API.

Specifically, convert chunk_write_fn to take a "void *data" parameter
instead of the commit-graph-specific "struct write_commit_graph_context"
pointer.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

commit-graph.c

@@ -1040,8 +1040,9 @@ struct write_commit_graph_context {
 };
 
 static int write_graph_chunk_fanout(struct hashfile *f,
-				    struct write_commit_graph_context *ctx)
+				    void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	int i, count = 0;
 	struct commit **list = ctx->commits.list;
 
@@ -1066,8 +1067,9 @@ static int write_graph_chunk_fanout(struct hashfile *f,
 }
 
 static int write_graph_chunk_oids(struct hashfile *f,
-				  struct write_commit_graph_context *ctx)
+				  void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	struct commit **list = ctx->commits.list;
 	int count;
 	for (count = 0; count < ctx->commits.nr; count++, list++) {
@@ -1085,8 +1087,9 @@ static const unsigned char *commit_to_sha1(size_t index, void *table)
 }
 
 static int write_graph_chunk_data(struct hashfile *f,
-				  struct write_commit_graph_context *ctx)
+				  void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	struct commit **list = ctx->commits.list;
 	struct commit **last = ctx->commits.list + ctx->commits.nr;
 	uint32_t num_extra_edges = 0;
@@ -1187,8 +1190,9 @@ static int write_graph_chunk_data(struct hashfile *f,
 }
 
 static int write_graph_chunk_generation_data(struct hashfile *f,
-					      struct write_commit_graph_context *ctx)
+					     void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	int i, num_generation_data_overflows = 0;
 
 	for (i = 0; i < ctx->commits.nr; i++) {
@@ -1208,8 +1212,9 @@ static int write_graph_chunk_generation_data(struct hashfile *f,
 }
 
 static int write_graph_chunk_generation_data_overflow(struct hashfile *f,
-						       struct write_commit_graph_context *ctx)
+						      void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	int i;
 	for (i = 0; i < ctx->commits.nr; i++) {
 		struct commit *c = ctx->commits.list[i];
@@ -1226,8 +1231,9 @@ static int write_graph_chunk_generation_data_overflow(struct hashfile *f,
 }
 
 static int write_graph_chunk_extra_edges(struct hashfile *f,
-					 struct write_commit_graph_context *ctx)
+					 void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	struct commit **list = ctx->commits.list;
 	struct commit **last = ctx->commits.list + ctx->commits.nr;
 	struct commit_list *parent;
@@ -1280,8 +1286,9 @@ static int write_graph_chunk_extra_edges(struct hashfile *f,
 }
 
 static int write_graph_chunk_bloom_indexes(struct hashfile *f,
-					   struct write_commit_graph_context *ctx)
+					   void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	struct commit **list = ctx->commits.list;
 	struct commit **last = ctx->commits.list + ctx->commits.nr;
 	uint32_t cur_pos = 0;
@@ -1315,8 +1322,9 @@ static void trace2_bloom_filter_settings(struct write_commit_graph_context *ctx)
 }
 
 static int write_graph_chunk_bloom_data(struct hashfile *f,
-					struct write_commit_graph_context *ctx)
+					void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	struct commit **list = ctx->commits.list;
 	struct commit **last = ctx->commits.list + ctx->commits.nr;
 
@@ -1737,8 +1745,9 @@ static int write_graph_chunk_base_1(struct hashfile *f,
 }
 
 static int write_graph_chunk_base(struct hashfile *f,
-				  struct write_commit_graph_context *ctx)
+				    void *data)
 {
+	struct write_commit_graph_context *ctx = data;
 	int num = write_graph_chunk_base_1(f, ctx->new_base_graph);
 
 	if (num != ctx->num_commit_graphs_after - 1) {
@@ -1750,7 +1759,7 @@ static int write_graph_chunk_base(struct hashfile *f,
 }
 
 typedef int (*chunk_write_fn)(struct hashfile *f,
-			      struct write_commit_graph_context *ctx);
+			      void *data);
 
 struct chunk_info {
 	uint32_t id;