commit-graph: clean up #includes

Our CodingGuidelines says that it's sufficient to include one of
'git-compat-util.h' and 'cache.h', but both 'commit-graph.c' and
'commit-graph.h' include both.  Let's include only 'git-compat-util.h'
to loose a bunch of unnecessary dependencies; but include 'hash.h',
because 'commit-graph.h' does require the definition of 'struct
object_id'.

'commit-graph.h' explicitly includes 'repository.h' and
'string-list.h', but only needs the declaration of a few structs from
them.  Drop these includes and forward-declare the necessary structs
instead.

'commit-graph.c' includes 'dir.h', but doesn't actually use anything
from there, so let's drop that #include as well.

Signed-off-by: SZEDER Gábor <[email protected]>
Signed-off-by: Derrick Stolee <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: szeder

commit-graph.c

@@ -1,7 +1,5 @@
-#include "cache.h"
-#include "config.h"
-#include "dir.h"
 #include "git-compat-util.h"
+#include "config.h"
 #include "lockfile.h"
 #include "pack.h"
 #include "packfile.h"

commit-graph.h

@@ -2,9 +2,6 @@
 #define COMMIT_GRAPH_H
 
 #include "git-compat-util.h"
-#include "repository.h"
-#include "string-list.h"
-#include "cache.h"
 #include "object-store.h"
 
 #define GIT_TEST_COMMIT_GRAPH "GIT_TEST_COMMIT_GRAPH"
@@ -22,6 +19,9 @@ void git_test_write_commit_graph_or_die(void);
 
 struct commit;
 struct bloom_filter_settings;
+struct repository;
+struct raw_object_store;
+struct string_list;
 
 char *get_commit_graph_filename(struct object_directory *odb);
 int open_commit_graph(const char *graph_file, int *fd, struct stat *st);