log-tree: replace include of revision.h with simple forward declaration

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

builtin/diff-tree.c

@@ -9,6 +9,7 @@
 #include "submodule.h"
 #include "read-cache-ll.h"
 #include "repository.h"
+#include "revision.h"
 #include "tree.h"
 
 static struct rev_info log_tree_opt;

log-tree.c

@@ -16,6 +16,7 @@
 #include "reflog-walk.h"
 #include "refs.h"
 #include "replace-object.h"
+#include "revision.h"
 #include "string-list.h"
 #include "color.h"
 #include "gpg-interface.h"

log-tree.h

@@ -1,7 +1,7 @@
 #ifndef LOG_TREE_H
 #define LOG_TREE_H
 
-#include "revision.h"
+struct rev_info;
 
 struct log_info {
 	struct commit *commit, *parent;