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/name-rev.c

@@ -558,7 +558,10 @@ static void name_rev_line(char *p, struct name_ref_data *data)
 	strbuf_release(&buf);
 }
 
-int cmd_name_rev(int argc, const char **argv, const char *prefix)
+int cmd_name_rev(int argc,
+		 const char **argv,
+		 const char *prefix,
+		 struct repository *repo UNUSED)
 {
 	struct mem_pool string_pool;
 	struct object_array revs = OBJECT_ARRAY_INIT;