git: update to v2.7.0

Update to git version v2.7.0.

* Upstream commit ed1c9977cb1b63e4270ad8bdf967a2d02580aa08 (Remove
  get_object_hash.) changed API:

  Convert all instances of get_object_hash to use an appropriate
  reference to the hash member of the oid member of struct object.
  This provides no functional change, as it is essentially a macro
  substitution.

Signed-off-by: Christian Hesse <mail@eworm.de>

ui-patch.c

@@ -48,7 +48,7 @@ void cgit_print_patch(const char *new_rev, const char *old_rev,
 			return;
 		}
 	} else if (commit->parents && commit->parents->item) {
-		hashcpy(old_rev_sha1, commit->parents->item->object.sha1);
+		hashcpy(old_rev_sha1, commit->parents->item->object.oid.hash);
 	} else {
 		hashclr(old_rev_sha1);
 	}