patch 8.1.0203: building with Perl 5.28 fails on Windows

Problem:    Building with Perl 5.28 fails on Windows.
Solution:   Define Perl_mg_get. (closes #3196)
diff --git a/src/version.c b/src/version.c
index a0f7483..66fabd9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -794,6 +794,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    203,
+/**/
     202,
 /**/
     201,