hash.h: move some oid-related declarations from cache.h

These defines and enum are all oid-related and as such seem to make
more sense being included in hash.h.  Further, moving them there
allows us to remove some includes of cache.h in other files.

The change to line-log.h might look unrelated, but line-log.h includes
diffcore.h, which previously included cache.h, which included the
kitchen sink.  Since this patch makes diffcore.h no longer include
cache.h, the compiler complains about the 'struct string_list *'
function parameter.  Add a forward declaration for struct string_list to
address this.

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

1 files changed, 3 insertions, 1 deletions

diff --git a/diffcore.h b/diffcore.h
index 9b588a1..1701ed5 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -4,9 +4,11 @@
 #ifndef DIFFCORE_H
 #define DIFFCORE_H
 
-#include "cache.h"
+#include "hash.h"
 
 struct diff_options;
+struct mem_pool;
+struct oid_array;
 struct repository;
 struct strintmap;
 struct strmap;