patch 8.1.0478: cannot build with perl using MinGW

Problem:    Cannot build with perl using MinGW.
Solution:   Add -I. (Ken takata, Cesar Romani)
diff --git a/src/version.c b/src/version.c
index 1268cdc..4a5c4b7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    478,
+/**/
     477,
 /**/
     476,