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/stripspace.c

@@ -29,7 +29,10 @@ enum stripspace_mode {
 	COMMENT_LINES
 };
 
-int cmd_stripspace(int argc, const char **argv, const char *prefix)
+int cmd_stripspace(int argc,
+		   const char **argv,
+		   const char *prefix,
+		   struct repository *repo UNUSED)
 {
 	struct strbuf buf = STRBUF_INIT;
 	enum stripspace_mode mode = STRIP_DEFAULT;