patch 8.1.0419: Cygwin: running cproto fails with -O2

Problem:    Cygwin: running cproto fails with -O2.
Solution:   Strip -O2 for cproto. (Ken Takata, closes #3465)
diff --git a/src/version.c b/src/version.c
index 079657e..bc3cbf3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    419,
+/**/
     418,
 /**/
     417,