symlinks.h: move declarations for symlinks.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/apply.c b/apply.c
index 2868cef..efe2dcb 100644
--- a/apply.c
+++ b/apply.c
@@ -30,6 +30,7 @@
 #include "apply.h"
 #include "entry.h"
 #include "setup.h"
+#include "symlinks.h"
 #include "wrapper.h"
 
 struct gitdiff_data {