base85.h: move declarations for base85.c functions from cache.h

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diff.c b/diff.c
index fa86d02..e697f78 100644
--- a/diff.c
+++ b/diff.c
@@ -4,6 +4,7 @@
 #include "cache.h"
 #include "abspath.h"
 #include "alloc.h"
+#include "base85.h"
 #include "config.h"
 #include "convert.h"
 #include "environment.h"