object-store.h: reduce unnecessary includes

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/object-file.c b/object-file.c
index 8e0df73..921a717 100644
--- a/object-file.c
+++ b/object-file.c
@@ -38,6 +38,7 @@
 #include "packfile.h"
 #include "object-file.h"
 #include "object-store.h"
+#include "oidtree.h"
 #include "promisor-remote.h"
 #include "setup.h"
 #include "submodule.h"
diff --git a/object-name.c b/object-name.c
index 5ccbe85..88d839f 100644
--- a/object-name.c
+++ b/object-name.c
@@ -14,6 +14,7 @@
 #include "remote.h"
 #include "dir.h"
 #include "oid-array.h"
+#include "oidtree.h"
 #include "packfile.h"
 #include "pretty.h"
 #include "object-store.h"
diff --git a/object-store.h b/object-store.h
index f9d2257..23ea86d 100644
--- a/object-store.h
+++ b/object-store.h
@@ -2,16 +2,16 @@
 #define OBJECT_STORE_H
 
 #include "object.h"
-#include "oidmap.h"
 #include "list.h"
-#include "oid-array.h"
-#include "strbuf.h"
 #include "thread-utils.h"
 #include "khash.h"
 #include "dir.h"
-#include "oidtree.h"
 #include "oidset.h"
 
+struct oidmap;
+struct oidtree;
+struct strbuf;
+
 struct object_directory {
 	struct object_directory *next;
 
diff --git a/submodule-config.c b/submodule-config.c
index 7fc0812..58dfbde 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -12,6 +12,7 @@
 #include "object-name.h"
 #include "object-store.h"
 #include "parse-options.h"
+#include "thread-utils.h"
 #include "tree-walk.h"
 
 /*