refs: move the remaining ref module declarations to refs.h

Some functions from the refs module were still declared in cache.h.
Move them to refs.h.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/blame.c b/builtin/blame.c
index b3e948e..1c998cb 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -6,6 +6,7 @@
  */
 
 #include "cache.h"
+#include "refs.h"
 #include "builtin.h"
 #include "blob.h"
 #include "commit.h"
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index b8182c2..d23f3be 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -5,6 +5,7 @@
  */
 #include "builtin.h"
 #include "cache.h"
+#include "refs.h"
 #include "commit.h"
 #include "object.h"
 #include "tag.h"
diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c
index 05f4c26..4ba7f28 100644
--- a/builtin/fmt-merge-msg.c
+++ b/builtin/fmt-merge-msg.c
@@ -1,5 +1,6 @@
 #include "builtin.h"
 #include "cache.h"
+#include "refs.h"
 #include "commit.h"
 #include "diff.h"
 #include "revision.h"
diff --git a/builtin/init-db.c b/builtin/init-db.c
index 4335738..49df78d 100644
--- a/builtin/init-db.c
+++ b/builtin/init-db.c
@@ -4,6 +4,7 @@
  * Copyright (C) Linus Torvalds, 2005
  */
 #include "cache.h"
+#include "refs.h"
 #include "builtin.h"
 #include "exec_cmd.h"
 #include "parse-options.h"
diff --git a/builtin/log.c b/builtin/log.c
index e67671e..3caa917 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -5,6 +5,7 @@
  *		 2006 Junio Hamano
  */
 #include "cache.h"
+#include "refs.h"
 #include "color.h"
 #include "commit.h"
 #include "diff.h"