patch 8.0.0638: cannot build with new MSVC version

Problem:    Cannot build with new MSVC version VS2017.
Solution:   Change the compiler arguments. (Leonardo Manera, closes #1731,
            closes #1747)
diff --git a/src/version.c b/src/version.c
index 23653c1..00733b3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    638,
+/**/
     637,
 /**/
     636,