global: prepare for hiding away repo-less config functions

We're about to hide config functions that implicitly depend on
`the_repository` behind the `USE_THE_REPOSITORY_VARIABLE` macro. This
will uncover a bunch of dependents that transitively relied on the
global variable, but didn't define the macro yet.

Adapt them such that we define the macro to prepare for this change.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs.c

@@ -2,6 +2,8 @@
  * The backend-independent part of the reference module.
  */
 
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "advice.h"
 #include "config.h"