tree-diff: no need to call "full" diff_tree_sha1 from show_path()

As described in previous commit, when recursing into sub-trees, we can
use lower-level tree walker, since its interface is now sha1 based.

The change is ok, because diff_tree_sha1() only invokes
ll_diff_tree_sha1(), and also, if base is empty, try_to_follow_renames().
But base is not empty here, as we have added a path and '/' before
recursing.

Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

tree-diff.c

@@ -6,6 +6,10 @@
 #include "diffcore.h"
 #include "tree.h"
 
+
+static int ll_diff_tree_sha1(const unsigned char *old, const unsigned char *new,
+			     const char *base_str, struct diff_options *opt);
+
 /*
  * Compare two tree entries, taking into account only path/S_ISDIR(mode),
  * but not their sha1's.
@@ -118,8 +122,8 @@ static void show_path(struct strbuf *base, struct diff_options *opt,
 
 	if (recurse) {
 		strbuf_addch(base, '/');
-		diff_tree_sha1(t1 ? t1->entry.sha1 : NULL,
-			       t2 ? t2->entry.sha1 : NULL, base->buf, opt);
+		ll_diff_tree_sha1(t1 ? t1->entry.sha1 : NULL,
+				  t2 ? t2->entry.sha1 : NULL, base->buf, opt);
 	}
 
 	strbuf_setlen(base, old_baselen);