name-hash.h: move declarations for name-hash.c from cache.h

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/helper/test-lazy-init-name-hash.c

@@ -2,6 +2,7 @@
 #include "test-tool.h"
 #include "cache.h"
 #include "environment.h"
+#include "name-hash.h"
 #include "parse-options.h"
 #include "repository.h"
 #include "setup.h"