builtin: remove USE_THE_REPOSITORY_VARIABLE from builtin.h

Instead of including USE_THE_REPOSITORY_VARIABLE by default on every
builtin, remove it from builtin.h and add it to all the builtins that
include builtin.h (by definition, that means all builtins/*.c).

Also, remove the include statement for repository.h since it gets
brought in through builtin.h.

The next step will be to migrate each builtin
from having to use the_repository.

Signed-off-by: John Cai <johncai86@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/commit.c b/builtin/commit.c
index 768d76a..fd1cc42 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -4,7 +4,7 @@
  * Copyright (c) 2007 Kristian Høgsberg <krh@redhat.com>
  * Based on git-commit.sh by Junio C Hamano and Linus Torvalds
  */
-
+#define USE_THE_REPOSITORY_VARIABLE
 #include "builtin.h"
 #include "advice.h"
 #include "config.h"