patch 8.2.2408: MinGW: "--preprocessor" flag no longer supported

Problem:    MinGW: "--preprocessor" flag no longer supported.
Solution:   Remove the flag, use the defaults. (Christopher Wellons,
            closes #7741)
diff --git a/src/version.c b/src/version.c
index 0602b9d..dce32e7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2408,
+/**/
     2407,
 /**/
     2406,