patch 8.1.0378: CI build failure

Problem:    CI build failure.
Solution:   Include vim.h as ../vim.h.  Fix compiler warning.
diff --git a/src/xdiff/xpatience.c b/src/xdiff/xpatience.c
index c187129..00af0ff 100644
--- a/src/xdiff/xpatience.c
+++ b/src/xdiff/xpatience.c
@@ -206,7 +206,7 @@
  */
 static struct entry *find_longest_common_sequence(struct hashmap *map)
 {
-	struct entry **sequence = xdl_malloc(map->nr * sizeof(struct entry *));
+	struct entry **sequence = (struct entry **)xdl_malloc(map->nr * sizeof(struct entry *));
 	int longest = 0, i;
 	struct entry *entry;