Declare lookup_replace_object() in cache.h, not in commit.h

The declaration is misplaced as the replace API is supposed to affect
not just commits, but all types of objects.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -763,6 +763,7 @@ static inline void *read_sha1_file(const unsigned char *sha1, enum object_type *
 {
 	return read_sha1_file_repl(sha1, type, size, NULL);
 }
+extern const unsigned char *lookup_replace_object(const unsigned char *sha1);
 extern int hash_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1);
 extern int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *return_sha1);
 extern int pretend_sha1_file(void *, unsigned long, enum object_type, unsigned char *);

commit.h

@@ -145,8 +145,6 @@ struct commit_graft *read_graft_line(char *buf, int len);
 int register_commit_graft(struct commit_graft *, int);
 struct commit_graft *lookup_commit_graft(const unsigned char *sha1);
 
-const unsigned char *lookup_replace_object(const unsigned char *sha1);
-
 extern struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2, int cleanup);
 extern struct commit_list *get_merge_bases_many(struct commit *one, int n, struct commit **twos, int cleanup);
 extern struct commit_list *get_octopus_merge_bases(struct commit_list *in);