builtin: add a repository parameter for builtin functions

In order to reduce the usage of the global the_repository, add a
parameter to builtin functions that will get passed a repository
variable.

This commit uses UNUSED on most of the builtin functions, as subsequent
commits will modify the actual builtins to pass the repository parameter
down.

Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/fetch-pack.c

@@ -43,7 +43,10 @@ static void add_sought_entry(struct ref ***sought, int *nr, int *alloc,
 	(*sought)[*nr - 1] = ref;
 }
 
-int cmd_fetch_pack(int argc, const char **argv, const char *prefix UNUSED)
+int cmd_fetch_pack(int argc,
+		   const char **argv,
+		   const char *prefix UNUSED,
+		   struct repository *repo UNUSED)
 {
 	int i, ret;
 	struct ref *ref = NULL;